/* =========================================================
   AI Math Solver — Design System
   Palette: paper #F7F5EF, ink #16213A, jade #1F7A6C, amber #E8A33D, coral #E1553A
   Type: Fraunces (display) / Space Grotesk (UI) / JetBrains Mono (equations)
   ========================================================= */

:root{
  --paper:#F7F5EF;
  --paper-dim:#EFEBE0;
  --ink:#16213A;
  --ink-soft:#3C4761;
  --jade:#1F7A6C;
  --jade-dark:#155A50;
  --jade-tint:#E4F1EE;
  --amber:#E8A33D;
  --coral:#E1553A;
  --line:#DAD5C6;
  --white:#FFFFFF;
  --radius:14px;
  --radius-sm:8px;
  --shadow:0 4px 24px rgba(22,33,58,0.08);
  --shadow-lg:0 12px 40px rgba(22,33,58,0.14);
  --max:1120px;
}

*,*::before,*::after{box-sizing:border-box;}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%;text-size-adjust:100%;}
body{
  margin:0;
  background:var(--paper);
  color:var(--ink);
  font-family:'Space Grotesk', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  line-height:1.55;
  -webkit-font-smoothing:antialiased;
  -webkit-tap-highlight-color:transparent;
  overflow-x:hidden;
}
a:focus-visible,button:focus-visible,input:focus-visible,textarea:focus-visible{
  outline:2px solid var(--jade);outline-offset:2px;
}
@media (max-width:480px){
  .container{padding:0 16px;}
  h1{font-size:clamp(1.7rem,7vw,2.4rem);}
}
img{max-width:100%;display:block;}
a{color:var(--jade-dark);}
h1,h2,h3,h4{
  font-family:'Fraunces', Georgia, serif;
  color:var(--ink);
  line-height:1.15;
  margin:0 0 .5em;
  font-weight:600;
}
h1{font-size:clamp(2rem,5vw,3.1rem);font-optical-sizing:auto;}
h2{font-size:clamp(1.5rem,3.4vw,2.1rem);}
h3{font-size:1.25rem;}
p{margin:0 0 1em;}
.mono{font-family:'JetBrains Mono', ui-monospace, Menlo, monospace;}
.container{max-width:var(--max);margin:0 auto;padding:0 20px;}
.eyebrow{
  display:inline-flex;align-items:center;gap:8px;
  font-size:.78rem;letter-spacing:.08em;text-transform:uppercase;
  color:var(--jade-dark);font-weight:600;margin-bottom:.8em;
}
.eyebrow::before{content:"";width:18px;height:2px;background:var(--coral);display:inline-block;}

/* ---------- Skip link ---------- */
.skip-link{position:absolute;left:-999px;top:0;background:var(--ink);color:#fff;padding:10px 16px;z-index:999;border-radius:0 0 8px 0;}
.skip-link:focus{left:0;}

/* ---------- Header ---------- */
.site-header{
  position:sticky;top:0;z-index:100;
  background:rgba(247,245,239,.92);
  backdrop-filter:blur(8px);
  border-bottom:1px solid var(--line);
}
.header-inner{
  max-width:var(--max);margin:0 auto;padding:14px 20px;
  display:flex;align-items:center;justify-content:space-between;gap:16px;
}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--ink);}
.brand-mark{
  width:36px;height:36px;border-radius:9px;background:var(--ink);
  color:var(--amber);display:flex;align-items:center;justify-content:center;
  font-family:'JetBrains Mono',monospace;font-weight:700;font-size:1.05rem;flex-shrink:0;
}
.brand-name{font-family:'Fraunces',serif;font-weight:600;font-size:1.15rem;}
.brand-name span{color:var(--jade-dark);}

.main-nav{display:flex;align-items:center;gap:22px;}
.main-nav a{
  color:var(--ink-soft);text-decoration:none;font-size:.95rem;font-weight:500;
}
.main-nav a:hover, .main-nav a.active{color:var(--jade-dark);}

/* ---- Header dropdown subcategories ---- */
.nav-item{position:relative;display:flex;align-items:center;}
.dropdown-toggle{
  display:flex;align-items:center;gap:5px;background:none;border:none;cursor:pointer;
  font-family:inherit;font-size:.95rem;font-weight:500;color:var(--ink-soft);padding:0;
}
.dropdown-toggle:hover, .nav-item.open .dropdown-toggle, .nav-item.nav-active .dropdown-toggle{color:var(--jade-dark);}
.dropdown-caret{
  width:8px;height:8px;border-right:2px solid currentColor;border-bottom:2px solid currentColor;
  transform:rotate(45deg);transition:transform .2s ease;margin-top:-3px;flex-shrink:0;
}
.nav-item.open .dropdown-caret{transform:rotate(-135deg);margin-top:1px;}

.dropdown-panel{
  position:absolute;top:calc(100% + 16px);left:50%;transform:translateX(-50%) translateY(-6px);
  background:var(--white);border:1px solid var(--line);border-radius:var(--radius);
  box-shadow:var(--shadow-lg);padding:10px;min-width:300px;
  opacity:0;visibility:hidden;pointer-events:none;
  transition:opacity .16s ease, transform .16s ease, visibility .16s;
  z-index:120;
}
.nav-item.open .dropdown-panel{opacity:1;visibility:visible;pointer-events:auto;transform:translateX(-50%) translateY(0);}
@media (hover:hover) and (pointer:fine){
  .nav-item.has-dropdown:hover .dropdown-panel{opacity:1;visibility:visible;pointer-events:auto;transform:translateX(-50%) translateY(0);}
  .nav-item.has-dropdown:hover .dropdown-caret{transform:rotate(-135deg);margin-top:1px;}
}
.dropdown-link{
  display:flex;align-items:flex-start;gap:10px;padding:10px 12px;border-radius:8px;
  text-decoration:none;color:var(--ink);
}
.dropdown-link:hover, .dropdown-link.active{background:var(--jade-tint);}
.dropdown-link-ic{
  width:30px;height:30px;border-radius:8px;background:var(--paper-dim);color:var(--jade-dark);
  display:flex;align-items:center;justify-content:center;flex-shrink:0;
  font-family:'JetBrains Mono',monospace;font-weight:700;font-size:.9rem;margin-top:1px;
}
.dropdown-link-body{display:flex;flex-direction:column;gap:2px;min-width:0;}
.dropdown-link-title{font-weight:600;font-size:.9rem;display:flex;align-items:center;gap:7px;line-height:1.3;}
.dropdown-link-desc{font-size:.79rem;color:var(--ink-soft);line-height:1.35;}
.dropdown-badge{
  font-size:.6rem;background:var(--amber);color:var(--ink);padding:2px 6px;border-radius:100px;
  font-weight:700;text-transform:uppercase;letter-spacing:.03em;flex-shrink:0;
}
.dropdown-divider{height:1px;background:var(--line);margin:6px 4px;}

@media (max-width:820px){
  .nav-item{width:100%;display:block;}
  .dropdown-toggle{width:100%;justify-content:space-between;padding:2px 0;font-size:1rem;}
  .dropdown-panel{
    position:static;transform:none;box-shadow:none;border:none;background:transparent;
    padding:2px 0 2px 4px;min-width:0;opacity:1;visibility:visible;pointer-events:auto;
    max-height:0;overflow:hidden;transition:max-height .25s ease;
  }
  .nav-item.open .dropdown-panel{max-height:600px;}
  .dropdown-link{padding:9px 8px;}
  .dropdown-link-ic{width:26px;height:26px;font-size:.8rem;}
}
.nav-cta{
  background:var(--ink);color:var(--paper)!important;padding:9px 16px;border-radius:100px;
  font-weight:600!important;
}
.nav-cta:hover{background:var(--jade-dark);}
.nav-toggle{display:none;background:none;border:1px solid var(--line);border-radius:8px;padding:8px 10px;cursor:pointer;}
.nav-toggle span{display:block;width:20px;height:2px;background:var(--ink);margin:4px 0;}

@media (max-width:820px){
  .main-nav{
    position:fixed;inset:64px 0 0 0;background:var(--paper);flex-direction:column;
    align-items:flex-start;padding:24px 24px;gap:18px;transform:translateX(100%);
    transition:transform .25s ease;overflow-y:auto;
  }
  .main-nav.open{transform:translateX(0);}
  .nav-toggle{display:block;}
  .nav-cta{margin-top:6px;}
}

/* ---------- Buttons ---------- */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  padding:13px 22px;border-radius:100px;font-weight:600;font-size:.97rem;
  text-decoration:none;border:none;cursor:pointer;transition:transform .15s ease, box-shadow .15s ease, background .15s ease;
  font-family:'Space Grotesk',sans-serif;
}
.btn-primary{background:var(--jade);color:#fff;box-shadow:var(--shadow);}
.btn-primary:hover{background:var(--jade-dark);transform:translateY(-1px);}
.btn-ghost{background:transparent;color:var(--ink);border:1.5px solid var(--line);}
.btn-ghost:hover{border-color:var(--ink);}
.btn-sm{padding:9px 14px;font-size:.85rem;}
.btn-block{width:100%;}

/* ---------- Hero / Solver ---------- */
.hero{padding:52px 0 20px;}
.hero-grid{display:grid;grid-template-columns:1fr;gap:10px;text-align:center;max-width:760px;margin:0 auto;}
.hero p.lead{font-size:1.1rem;color:var(--ink-soft);max-width:600px;margin:0 auto 6px;}

.solver-card{
  background:var(--white);
  border:1px solid var(--line);
  border-radius:var(--radius);
  box-shadow:var(--shadow-lg);
  padding:26px;
  margin:28px auto 0;
  max-width:820px;
  position:relative;
  background-image:
    linear-gradient(var(--jade-tint) 1px, transparent 1px),
    linear-gradient(90deg, var(--jade-tint) 1px, transparent 1px);
  background-size:28px 28px;
  background-position:-1px -1px;
  background-color:#fff;
}
.solver-card::before{
  content:"";position:absolute;inset:0;border-radius:var(--radius);
  background:linear-gradient(180deg, rgba(255,255,255,.85), rgba(255,255,255,.97) 40%);
  pointer-events:none;
}
.solver-card > *{position:relative;}

.solver-input-row{display:flex;gap:10px;flex-wrap:wrap;}
.solver-input{
  flex:1 1 320px;
  font-family:'JetBrains Mono',monospace;
  font-size:1.15rem;
  padding:16px 18px;
  border:2px solid var(--line);
  border-radius:var(--radius-sm);
  background:#fff;
  color:var(--ink);
  outline:none;
  transition:border-color .15s ease;
}
.solver-input:focus{border-color:var(--jade);}
.solver-actions{display:flex;gap:10px;flex-wrap:wrap;}
.btn.processing{position:relative;color:transparent!important;pointer-events:none;}
.btn.processing::after{
  content:"";position:absolute;inset:0;margin:auto;width:16px;height:16px;
  border:2px solid rgba(0,0,0,.15);border-top-color:var(--jade);
  border-radius:50%;animation:dock-spin .7s linear infinite;
}
.ocr-status-inline{font-size:.82rem;color:var(--jade-dark);margin:8px 0 0;width:100%;}

.example-chips{display:flex;flex-wrap:wrap;gap:8px;margin-top:14px;}
.chip{
  font-family:'JetBrains Mono',monospace;
  font-size:.82rem;background:var(--jade-tint);color:var(--jade-dark);
  border:1px solid transparent;padding:7px 12px;border-radius:100px;cursor:pointer;
  transition:background .15s ease;
}
.chip:hover{background:#d5ece7;}
.chip:before{content:"try  ";opacity:.55;}

.solver-mode-label{
  font-size:.75rem;text-transform:uppercase;letter-spacing:.06em;color:var(--ink-soft);
  margin-top:14px;display:flex;gap:6px;align-items:center;
}

.solution-panel{
  margin-top:22px;border-top:1px dashed var(--line);padding-top:20px;
}
.solution-answer{
  display:flex;align-items:center;gap:14px;flex-wrap:wrap;
  background:var(--jade-tint);border-radius:var(--radius-sm);
  padding:16px 18px;margin-bottom:16px;
}
.solution-answer .label{font-size:.78rem;text-transform:uppercase;letter-spacing:.06em;color:var(--jade-dark);font-weight:700;}
.solution-answer .value{font-family:'JetBrains Mono',monospace;font-size:1.3rem;font-weight:700;color:var(--ink);}
.verified-note{font-family:'Caveat',cursive;font-weight:600;color:var(--coral);font-size:1.2rem;margin-left:auto;transform:rotate(-2deg);white-space:nowrap;}

.step{
  display:grid;grid-template-columns:34px 1fr;gap:14px;padding:12px 0;
  border-bottom:1px solid var(--paper-dim);
}
.step:last-child{border-bottom:none;}
.step-num{
  width:30px;height:30px;border-radius:50%;background:var(--ink);color:var(--amber);
  display:flex;align-items:center;justify-content:center;font-family:'JetBrains Mono',monospace;
  font-size:.82rem;font-weight:700;
}
.step-body .step-title{font-weight:600;margin-bottom:2px;font-size:.94rem;color:var(--ink-soft);}
.step-body .step-expr{font-family:'JetBrains Mono',monospace;font-size:1.08rem;color:var(--ink);white-space:pre-wrap;line-height:1.5;}
.step-note{
  display:none;margin-top:8px;padding:9px 12px;background:var(--jade-tint);
  border-left:3px solid var(--jade);border-radius:0 8px 8px 0;
  font-size:.84rem;line-height:1.5;color:var(--ink-soft);
}
.solution-panel.advanced .step-note{display:block;}
#explainBtn[aria-pressed="true"]{background:var(--jade);color:#fff;border-color:var(--jade);}

.solver-error{
  background:#FBEAE5;color:#9A3421;border:1px solid #F2C7BA;border-radius:var(--radius-sm);
  padding:14px 16px;margin-top:16px;font-size:.92rem;
}
.result-tools{display:flex;gap:10px;margin-top:18px;flex-wrap:wrap;align-items:center;}

/* ---------- Post-solve feedback ---------- */
.solution-feedback{
  display:flex;align-items:center;gap:12px;flex-wrap:wrap;
  margin-top:14px;padding-top:14px;border-top:1px dashed var(--line);
  font-size:.88rem;color:var(--ink-soft);
}
.feedback-prompt{font-weight:600;}
.feedback-buttons{display:flex;gap:6px;}
.feedback-btn{
  width:36px;height:36px;border-radius:50%;
  background:transparent;border:1.5px solid var(--line);cursor:pointer;
  font-size:1rem;line-height:1;display:flex;align-items:center;justify-content:center;
  transition:transform .15s ease, border-color .15s ease, background .15s ease, opacity .15s ease;
}
.feedback-btn:hover:not(:disabled){border-color:var(--ink);transform:translateY(-1px);}
.feedback-btn.selected{background:var(--jade-tint);border-color:var(--jade);}
.feedback-btn:disabled{cursor:default;}
.feedback-btn:disabled:not(.selected){opacity:.4;}
.feedback-thanks{font-family:'Caveat',cursive;font-weight:600;font-size:1.15rem;color:var(--jade-dark);}

.solver-dock .solution-feedback{border-top-color:var(--dock-line);color:var(--dock-text-soft);}
.solver-dock .feedback-btn{border-color:var(--dock-line);}
.solver-dock .feedback-btn:hover:not(:disabled){border-color:var(--dock-accent);}
.solver-dock .feedback-btn.selected{background:rgba(240,166,60,.16);border-color:var(--dock-accent);}
.solver-dock .feedback-thanks{color:var(--dock-accent);}

/* ---------- Number line visualization (linear inequalities) ---------- */
.number-line-wrap{
  background:var(--paper);border:1px solid var(--line);border-radius:var(--radius-sm);
  padding:14px 10px 6px;margin-bottom:16px;
}
.number-line-wrap .nl-caption{
  font-size:.75rem;text-transform:uppercase;letter-spacing:.06em;color:var(--ink-soft);
  padding:0 8px 6px;
}
.number-line-wrap svg{display:block;width:100%;height:auto;}

/* ---------- Recent problems (solve history) ---------- */
/* ---------- Follow-up chat ---------- */
.followup-chat{margin-top:18px;border-top:1px solid var(--paper-dim);padding-top:16px;}
.followup-toggle{
  display:flex;align-items:center;justify-content:space-between;gap:10px;width:100%;
  background:var(--jade-tint);border:1px solid var(--line);border-radius:var(--radius-sm);
  padding:11px 14px;cursor:pointer;font-family:inherit;font-size:.92rem;font-weight:600;color:var(--jade-dark);
  text-align:left;
}
.followup-toggle:hover{border-color:var(--jade);}
.followup-toggle .followup-hint{font-weight:400;font-size:.78rem;color:var(--ink-soft);}
@media (max-width:640px){.followup-toggle{flex-direction:column;align-items:flex-start;gap:4px;}}
.followup-body{margin-top:12px;}
.followup-log{max-height:340px;overflow-y:auto;display:flex;flex-direction:column;gap:10px;margin-bottom:12px;}
.followup-msg{padding:10px 13px;border-radius:var(--radius-sm);font-size:.9rem;line-height:1.5;max-width:88%;}
.followup-msg.bot{background:var(--paper-dim);color:var(--ink);align-self:flex-start;}
.followup-msg.user{background:var(--ink);color:var(--paper);align-self:flex-end;}
.followup-msg .mono{font-family:'JetBrains Mono',monospace;}
.followup-suggestions{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:12px;}
.followup-chip{
  background:var(--white);border:1px solid var(--line);border-radius:100px;padding:6px 12px;
  font-size:.8rem;color:var(--ink-soft);cursor:pointer;font-family:inherit;
}
.followup-chip:hover{border-color:var(--jade);color:var(--jade-dark);}
.followup-form{display:flex;gap:8px;}
.followup-input{
  flex:1;border:1px solid var(--line);border-radius:var(--radius-sm);padding:10px 12px;
  font-family:inherit;font-size:.9rem;background:var(--white);color:var(--ink);
}
.followup-input:focus{outline:2px solid var(--jade);outline-offset:1px;}

/* ---------- Geometry / Statistics / Matrix tool forms ---------- */
.tool-form-row{display:flex;gap:14px;flex-wrap:wrap;align-items:flex-end;margin-bottom:16px;}
.tool-select-field{display:flex;flex-direction:column;gap:6px;font-size:.85rem;color:var(--ink-soft);font-weight:600;}
.tool-select-field select{
  border:1px solid var(--line);border-radius:var(--radius-sm);padding:10px 12px;background:var(--white);
  color:var(--ink);font-family:inherit;font-size:.95rem;min-width:220px;
}
.geo-fields{display:flex;gap:14px;flex-wrap:wrap;margin-bottom:16px;}
.geo-field{display:flex;flex-direction:column;gap:6px;font-size:.85rem;color:var(--ink-soft);font-weight:600;}
.geo-field input{
  border:1px solid var(--line);border-radius:var(--radius-sm);padding:10px 12px;background:var(--white);
  color:var(--ink);font-family:'JetBrains Mono',monospace;font-size:.95rem;width:140px;
}
.geo-field input:focus, .tool-select-field select:focus{outline:2px solid var(--jade);outline-offset:1px;}
.mat-grid-wrap{display:flex;flex-direction:column;gap:8px;margin-bottom:6px;}
.mat-grid-wrap .mat-label{font-size:.8rem;font-weight:700;color:var(--ink-soft);text-transform:uppercase;letter-spacing:.04em;}
.mat-grid{display:grid;gap:8px;}
.mat-cell{
  width:64px;height:44px;text-align:center;border:1px solid var(--line);border-radius:var(--radius-sm);
  background:var(--white);color:var(--ink);font-family:'JetBrains Mono',monospace;font-size:1rem;
}
.mat-cell:focus{outline:2px solid var(--jade);outline-offset:1px;}
.mat-pair{display:flex;gap:28px;flex-wrap:wrap;margin-bottom:16px;}
.stat-input{
  width:100%;min-height:80px;border:1px solid var(--line);border-radius:var(--radius-sm);padding:12px;
  font-family:'JetBrains Mono',monospace;font-size:.95rem;color:var(--ink);background:var(--white);resize:vertical;
}
.stat-input:focus{outline:2px solid var(--jade);outline-offset:1px;}

.solve-history{margin-top:16px;}
.solve-history .sh-label{
  font-size:.75rem;text-transform:uppercase;letter-spacing:.06em;color:var(--ink-soft);
  display:flex;align-items:center;gap:8px;margin-bottom:8px;
}
.solve-history .sh-clear{
  background:none;border:none;color:var(--ink-soft);text-decoration:underline;
  cursor:pointer;font-size:.75rem;padding:0;margin-left:auto;
}
.solve-history .sh-clear:hover{color:var(--coral);}
.chip.history-chip:before{content:"↻  ";opacity:.55;}

/* ---------- Syntax reference table ---------- */
.syntax-table{width:100%;border-collapse:collapse;margin-top:10px;font-size:.92rem;}
.syntax-table th,.syntax-table td{text-align:left;padding:10px 12px;border-bottom:1px solid var(--line);}
.syntax-table th{font-family:'Space Grotesk',sans-serif;font-size:.76rem;text-transform:uppercase;letter-spacing:.06em;color:var(--jade-dark);}
.syntax-table td.mono{white-space:nowrap;}
.syntax-table tr:last-child td{border-bottom:none;}
.new-badge{
  display:inline-block;background:var(--coral);color:#fff;font-size:.65rem;font-weight:700;
  letter-spacing:.04em;text-transform:uppercase;padding:2px 7px;border-radius:100px;
  margin-left:8px;vertical-align:middle;
}

/* ---------- Sections ---------- */
section{padding:56px 0;}
.section-tight{padding:36px 0;}
.section-alt{background:var(--white);border-top:1px solid var(--line);border-bottom:1px solid var(--line);}
.two-col{display:grid;grid-template-columns:1fr 1fr;gap:40px;align-items:start;}
@media (max-width:760px){.two-col{grid-template-columns:1fr;}}

.card-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:22px;}
@media (max-width:860px){.card-grid{grid-template-columns:repeat(2,1fr);}}
@media (max-width:600px){.card-grid{grid-template-columns:1fr;}}

.info-card{
  background:var(--white);border:1px solid var(--line);border-radius:var(--radius);
  padding:26px;transition:box-shadow .18s ease,transform .18s ease,border-color .18s ease;
}
.info-card:hover{box-shadow:var(--shadow);transform:translateY(-2px);border-color:var(--jade-tint);}
.info-card .num{
  font-family:'JetBrains Mono',monospace;font-weight:700;font-size:.95rem;
  margin-bottom:14px;display:flex;align-items:center;justify-content:center;
  width:38px;height:38px;border-radius:10px;background:var(--ink);color:var(--amber);
}

.testi-card{
  background:var(--jade-tint);border-radius:var(--radius);padding:24px;display:flex;flex-direction:column;
}
.testi-stars{color:var(--amber);letter-spacing:2px;font-size:.9rem;margin-bottom:10px;}
.testi-card p{font-style:italic;color:var(--ink-soft);}
.testi-foot{display:flex;align-items:center;gap:10px;margin-top:auto;padding-top:6px;}
.testi-avatar{
  width:34px;height:34px;border-radius:50%;background:var(--ink);color:var(--amber);
  display:flex;align-items:center;justify-content:center;font-family:'Fraunces',serif;
  font-weight:700;font-size:.85rem;flex-shrink:0;
}
.testi-name{font-weight:700;font-size:.88rem;color:var(--ink);}

/* ---------- Reviews ---------- */
.reviews-summary{
  display:flex;gap:40px;align-items:center;flex-wrap:wrap;
  margin:22px 0 32px;padding:26px;background:var(--white);
  border:1px solid var(--line);border-radius:var(--radius);
}
.reviews-score{display:flex;align-items:center;gap:16px;}
.reviews-score-num{font-family:'Fraunces',serif;font-size:3rem;font-weight:700;color:var(--ink);line-height:1;}
.reviews-score-stars{color:var(--amber);letter-spacing:2px;font-size:1.05rem;}
.reviews-score-sub{color:var(--ink-soft);font-size:.85rem;margin-top:4px;}
.reviews-bars{flex:1;min-width:230px;display:flex;flex-direction:column;gap:7px;}
.reviews-bar-row{display:grid;grid-template-columns:26px 1fr 36px;align-items:center;gap:10px;font-size:.8rem;color:var(--ink-soft);}
.reviews-bar{height:8px;background:var(--jade-tint);border-radius:99px;overflow:hidden;}
.reviews-bar span{display:block;height:100%;background:var(--amber);border-radius:99px;}
.review-card{position:relative;}
.review-head{display:flex;justify-content:space-between;align-items:flex-start;gap:10px;}
.review-date{font-size:.76rem;color:var(--ink-soft);white-space:nowrap;}
.review-verified{
  display:inline-flex;align-items:center;gap:4px;font-size:.74rem;
  color:var(--jade-dark);font-weight:700;margin-top:10px;
}
@media (max-width:600px){
  .reviews-summary{flex-direction:column;align-items:flex-start;gap:20px;}
}

/* ---- Tool-card icon color variants (visual rhythm across the "what it solves" grid) ---- */
.tool-card-ic{background:var(--jade-tint);color:var(--jade-dark);}
.tool-card--amber .tool-card-ic{background:#FDECD8;color:#9A5B0E;}
.tool-card--coral .tool-card-ic{background:#FBE3E3;color:#9A3421;}
.tool-card--ink .tool-card-ic{background:#E7E9F1;color:var(--ink);}

/* ---------- Sticky solver CTA (blog/content pages) ---------- */
.sticky-cta{
  position:fixed;left:0;right:0;bottom:0;z-index:90;
  background:var(--ink);color:#fff;
  padding:12px 20px;
  display:flex;align-items:center;justify-content:center;gap:16px;flex-wrap:wrap;
  box-shadow:0 -6px 20px rgba(0,0,0,.15);
  transform:translateY(100%);transition:transform .3s ease;
}
.sticky-cta.show{transform:translateY(0);}
.sticky-cta span{font-size:.92rem;color:#D9DEE8;}
.sticky-cta .btn-primary{background:var(--amber);color:var(--ink);}
.sticky-cta .btn-primary:hover{background:#f3b45c;}

/* ---------- Blog ---------- */
.post-list{display:flex;flex-direction:column;gap:0;}
.post-row{
  display:grid;grid-template-columns:120px 1fr;gap:20px;padding:22px 0;
  border-bottom:1px solid var(--line);align-items:start;
}
@media (max-width:600px){.post-row{grid-template-columns:1fr;}}
.post-row .tag{
  font-family:'JetBrains Mono',monospace;font-size:.72rem;color:var(--jade-dark);
  background:var(--jade-tint);padding:5px 9px;border-radius:6px;display:inline-block;height:fit-content;
}
.post-row h3{margin-bottom:6px;}
.post-row h3 a{text-decoration:none;color:var(--ink);}
.post-row h3 a:hover{color:var(--jade-dark);}
.post-row p{color:var(--ink-soft);margin-bottom:0;font-size:.95rem;}

.article-hero{padding:40px 0 10px;}
.article-meta{color:var(--ink-soft);font-size:.88rem;margin-bottom:6px;}
.article-body{max-width:720px;margin:0 auto;padding-bottom:60px;}
.article-body h2{margin-top:1.6em;scroll-margin-top:90px;}
.article-body h3{margin-top:1.2em;scroll-margin-top:90px;}
.article-body ul,.article-body ol{padding-left:1.3em;margin-bottom:1.2em;}
.article-body li{margin-bottom:.4em;}
.article-body .mono{word-break:break-word;overflow-wrap:break-word;}
.article-body blockquote{
  margin:1.5em 0;padding:14px 18px;border-left:3px solid var(--jade);background:var(--jade-tint);
  border-radius:0 8px 8px 0;color:var(--ink-soft);
}
.inline-solver-link{
  display:block;background:var(--jade-tint);border:1px dashed var(--jade);border-radius:var(--radius-sm);
  padding:16px 18px;margin:1.6em 0;text-decoration:none;color:var(--ink);font-weight:600;
}
.inline-solver-link:hover{background:#DCEFEA;}

/* ---- Breadcrumb ---- */
.breadcrumb{
  display:flex;flex-wrap:wrap;align-items:center;gap:6px;
  font-size:.82rem;color:var(--ink-soft);padding:14px 0 0;
}
.breadcrumb a{color:var(--ink-soft);text-decoration:none;}
.breadcrumb a:hover{color:var(--jade-dark);}
.breadcrumb .sep{color:var(--line);}
.breadcrumb .current{color:var(--ink);font-weight:500;}
@media (max-width:480px){
  .breadcrumb{font-size:.76rem;}
}

/* ---- Author byline ---- */
.article-byline{
  display:flex;align-items:center;gap:12px;margin:14px 0 4px;padding-bottom:18px;
  border-bottom:1px solid var(--line);
}
.byline-avatar{
  width:38px;height:38px;border-radius:50%;background:var(--jade-tint);color:var(--jade-dark);
  display:flex;align-items:center;justify-content:center;font-family:'Fraunces',serif;font-weight:600;
  flex-shrink:0;font-size:1rem;
}
.byline-text{font-size:.86rem;color:var(--ink-soft);line-height:1.35;}
.byline-text strong{color:var(--ink);font-weight:600;}

/* ---- Table of contents ---- */
.article-toc{
  background:var(--white);border:1px solid var(--line);border-radius:var(--radius-sm);
  padding:6px 20px;margin:1.8em 0 2em;
}
.article-toc summary{
  cursor:pointer;padding:12px 0;font-weight:600;font-family:'Space Grotesk',sans-serif;
  font-size:.92rem;color:var(--ink);list-style:none;display:flex;align-items:center;justify-content:space-between;
}
.article-toc summary::-webkit-details-marker{display:none;}
.article-toc summary::after{content:"▾";color:var(--jade-dark);transition:transform .2s ease;}
.article-toc[open] summary::after{transform:rotate(180deg);}
.article-toc ol{list-style:decimal;padding-left:1.2em;margin:0 0 16px;}
.article-toc li{margin-bottom:6px;font-size:.92rem;}
.article-toc a{color:var(--ink-soft);text-decoration:none;}
.article-toc a:hover{color:var(--jade-dark);}
@media (min-width:960px){
  /* On wide screens, keep TOC open by default via HTML `open` attribute (set per-page) */
  .article-toc summary{cursor:default;}
}

/* ---- Responsive tables inside article content ---- */
.table-scroll{overflow-x:auto;margin:1.5em 0;-webkit-overflow-scrolling:touch;}
.table-scroll table{width:100%;border-collapse:collapse;font-size:.92rem;min-width:480px;}
.table-scroll th,.table-scroll td{padding:10px 14px;border-bottom:1px solid var(--line);text-align:left;}
.table-scroll th{background:var(--paper-dim);font-family:'Space Grotesk',sans-serif;font-weight:600;font-size:.82rem;text-transform:uppercase;letter-spacing:.04em;color:var(--ink-soft);}
.table-scroll tr:last-child td{border-bottom:none;}

/* ---- Related posts / read next ---- */
.related-posts{margin:2.4em 0 0;padding-top:1.6em;border-top:1px solid var(--line);}
.related-posts h2{margin-top:0;font-size:1.3rem;}
.related-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:16px;}
@media (max-width:600px){.related-grid{grid-template-columns:1fr;}}
.related-card{
  display:block;background:var(--white);border:1px solid var(--line);border-radius:var(--radius-sm);
  padding:16px 18px;text-decoration:none;transition:border-color .15s ease,transform .15s ease;
}
.related-card:hover{border-color:var(--jade);transform:translateY(-2px);}
.related-card .tag{
  font-family:'JetBrains Mono',monospace;font-size:.7rem;color:var(--jade-dark);
  background:var(--jade-tint);padding:3px 8px;border-radius:6px;display:inline-block;margin-bottom:8px;
}
.related-card h3{font-size:1rem;margin-bottom:4px;color:var(--ink);}
.related-card p{font-size:.85rem;color:var(--ink-soft);margin:0;}

/* ---------- Footer ---------- */
.site-footer{background:var(--ink);color:#B9C1D4;padding:50px 0 26px;margin-top:40px;}
.footer-grid{display:grid;grid-template-columns:2fr 1fr 1fr 1fr;gap:28px;}
@media (max-width:700px){.footer-grid{grid-template-columns:1fr 1fr;}}
.site-footer h4{color:#fff;font-family:'Space Grotesk',sans-serif;font-size:.85rem;text-transform:uppercase;letter-spacing:.06em;margin-bottom:14px;}
.site-footer a{color:#B9C1D4;text-decoration:none;font-size:.92rem;}
.site-footer a:hover{color:#fff;}
.footer-links{list-style:none;padding:0;margin:0;display:flex;flex-direction:column;gap:9px;}
.footer-bottom{
  border-top:1px solid #2A3555;margin-top:36px;padding-top:20px;
  display:flex;justify-content:space-between;flex-wrap:wrap;gap:10px;font-size:.82rem;color:#8993AC;
}
.footer-brand p{color:#8993AC;font-size:.9rem;max-width:320px;}

/* ---------- Misc ---------- */
.badge-row{display:flex;gap:10px;flex-wrap:wrap;margin-top:18px;justify-content:center;}
.badge{
  font-size:.78rem;color:var(--ink-soft);background:var(--white);border:1px solid var(--line);
  padding:6px 12px;border-radius:100px;
}
.center{text-align:center;}
.narrow{max-width:680px;margin:0 auto;}
.visually-hidden{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0,0,0,0);}

/* ---- FAQ accordion (native <details>, no JS required) ---- */
.faq-item{border-bottom:1px solid var(--line);padding:4px 0;}
.faq-item summary{
  list-style:none;cursor:pointer;padding:16px 30px 16px 2px;position:relative;
  font-family:'Fraunces',serif;font-weight:600;font-size:1.05rem;color:var(--ink);
}
.faq-item summary::-webkit-details-marker{display:none;}
.faq-item summary::after{
  content:"+";position:absolute;right:2px;top:50%;transform:translateY(-50%);
  font-family:'Space Grotesk',sans-serif;font-size:1.3rem;font-weight:400;color:var(--jade-dark);
  transition:transform .2s ease;
}
.faq-item[open] summary::after{transform:translateY(-50%) rotate(45deg);}
.faq-item summary:hover{color:var(--jade-dark);}
.faq-item p{color:var(--ink-soft);padding:0 30px 16px 2px;margin:0;}

@media (max-width:500px){
  .solver-card{padding:18px;}
  .card-grid{gap:16px;}
  section{padding:40px 0;}
}

/* =========================================================
   App shell (homepage "workspace" layout)
   ========================================================= */
body.app-shell{overflow-x:hidden;}
.app-shell .skip-link{z-index:999;}
.app-container{display:flex;min-height:100vh;}

/* ---- Sidebar ---- */
.app-sidebar{
  width:250px;flex-shrink:0;background:var(--white);
  border-right:1px solid var(--line);
  display:flex;flex-direction:column;
  padding:20px 16px;position:sticky;top:0;height:100vh;overflow-y:auto;
}
.app-sidebar .brand{margin-bottom:22px;padding:0 6px;}
.sidebar-nav{display:flex;flex-direction:column;gap:2px;margin-bottom:18px;}
.sidebar-link{
  display:flex;align-items:center;gap:11px;padding:10px 12px;border-radius:10px;
  color:var(--ink-soft);text-decoration:none;font-weight:500;font-size:.95rem;
  transition:background .15s ease,color .15s ease;
}
.sidebar-link .ic{width:18px;height:18px;flex-shrink:0;display:inline-flex;align-items:center;justify-content:center;}
.sidebar-link:hover{background:var(--paper-dim);color:var(--ink);}
.sidebar-link.active{background:#FCEFDC;color:#9A5B0E;font-weight:600;}
.sidebar-section-label{
  font-size:.72rem;text-transform:uppercase;letter-spacing:.07em;color:#9CA3B8;
  padding:14px 12px 6px;font-weight:600;
}
.sidebar-bottom{margin-top:auto;display:flex;flex-direction:column;gap:2px;padding-top:14px;border-top:1px solid var(--line);}
.sidebar-close{display:none;position:absolute;top:16px;right:16px;background:none;border:none;font-size:1.3rem;cursor:pointer;color:var(--ink-soft);}

/* ---- Main workspace ---- */
.app-main{flex:1;min-width:0;padding:0 24px 60px;}
.app-topbar{
  display:flex;align-items:center;justify-content:space-between;gap:12px;
  padding:18px 4px;
}
.mobile-menu-btn{
  display:none;background:var(--white);border:1px solid var(--line);border-radius:9px;
  width:40px;height:40px;font-size:1.15rem;cursor:pointer;position:fixed;top:14px;left:14px;z-index:120;
  box-shadow:var(--shadow);
}
.app-topbar-links{display:flex;gap:18px;}
.app-topbar-links a{color:var(--ink-soft);text-decoration:none;font-size:.92rem;font-weight:500;}
.app-topbar-links a:hover{color:var(--jade-dark);}

/* ---- Hero stage: everything from the H1 down to the solver dock lives in
   one visually-contained "stage" so their edges line up and the whole block
   reads as a single, considered unit rather than stacked, disconnected rows. ---- */
.hero-stage{
  position:relative;
  padding:38px 0 44px;
  margin:0 -24px 8px;
  overflow:hidden;
  isolation:isolate;
}
.hero-stage::before,.hero-stage::after{
  content:"";position:absolute;z-index:-1;border-radius:50%;filter:blur(60px);opacity:.55;
}
.hero-stage::before{
  width:420px;height:420px;background:radial-gradient(circle,var(--jade-tint) 0%,transparent 72%);
  top:-160px;left:calc(50% - 520px);
}
.hero-stage::after{
  width:380px;height:380px;background:radial-gradient(circle,#FCEFDC 0%,transparent 72%);
  top:-120px;right:calc(50% - 500px);
}
.hero-stage-inner{max-width:1180px;margin:0 auto;padding:0 24px;}

/* ---- Hero split: copy on the left, scratchpad signature visual on the right ---- */
.hero-split{display:grid;grid-template-columns:1.05fr .95fr;gap:48px;align-items:center;}
@media (max-width:900px){.hero-split{grid-template-columns:1fr;gap:8px;}}

.hero-kicker{
  display:flex;align-items:center;justify-content:flex-start;gap:8px;
  margin:0 0 16px;font-size:.78rem;font-weight:700;letter-spacing:.05em;
  text-transform:uppercase;color:var(--jade-dark);flex-wrap:wrap;
}
.hero-kicker .stars{color:var(--amber);letter-spacing:1px;font-size:.85rem;}
.hero-kicker .divider{width:3px;height:3px;border-radius:50%;background:var(--line);display:inline-block;}
.hero-kicker .muted{color:var(--ink-soft);font-weight:500;text-transform:none;letter-spacing:0;}

.app-hero{max-width:560px;margin:0;text-align:left;}
.app-hero h1{font-size:clamp(2.1rem,3.6vw,2.9rem);}
.app-hero h1 em{font-style:italic;color:var(--jade-dark);}
.app-hero p{color:var(--ink-soft);font-size:1.08rem;max-width:520px;margin:0;}

.hero-cta-row{display:flex;align-items:center;gap:18px;flex-wrap:wrap;margin:22px 0 4px;}
.btn-coral{background:var(--coral);color:#fff;box-shadow:0 10px 24px rgba(225,85,58,.28);}
.btn-coral:hover{background:#C8462E;transform:translateY(-1px);}
.hero-cta-secondary{color:var(--ink);font-weight:600;font-size:.95rem;text-decoration:none;display:inline-flex;align-items:center;gap:6px;}
.hero-cta-secondary:hover{color:var(--jade-dark);}

/* ---- Scratchpad: the site's signature visual — a worked problem with
   tutor-style handwritten margin notes, standing in for a stock hero image ---- */
.hero-scratchpad{
  background:var(--white);border-radius:20px;box-shadow:var(--shadow-lg);
  padding:24px 24px 20px;position:relative;transform:rotate(1deg);
  border:1px solid var(--line);
}
.hero-scratchpad::before{
  content:"";position:absolute;inset:0;border-radius:20px;pointer-events:none;
  background:repeating-linear-gradient(var(--white) 0 37px, var(--paper-dim) 37px 38px);
  opacity:.5;
}
.pad-head{display:flex;justify-content:space-between;align-items:center;margin-bottom:14px;position:relative;}
.pad-tag{font-size:.72rem;text-transform:uppercase;letter-spacing:.06em;color:var(--jade-dark);font-weight:700;background:var(--jade-tint);padding:4px 10px;border-radius:100px;}
.pad-dots{display:flex;gap:5px;}
.pad-dots span{width:8px;height:8px;border-radius:50%;background:var(--line);display:block;}
.pad-eq{font-family:'JetBrains Mono',monospace;font-size:1.24rem;font-weight:700;color:var(--ink);margin:16px 0;position:relative;}
.pad-eq .pad-note{position:absolute;right:0;top:-24px;font-family:'Caveat',cursive;font-weight:600;font-size:1.1rem;color:var(--coral);transform:rotate(-3deg);}
.pad-divider{height:1px;background:var(--line);margin:20px 0 16px;}
.pad-answer{display:inline-flex;align-items:center;gap:8px;background:var(--ink);color:var(--paper);padding:10px 16px;border-radius:10px;font-family:'JetBrains Mono',monospace;font-weight:700;font-size:1rem;}
.pad-answer .ok{color:#8FE3C2;}
.pad-margin-note{font-family:'Caveat',cursive;font-weight:600;color:var(--jade-dark);font-size:1.25rem;margin-top:14px;transform:rotate(-1deg);}
@media (max-width:900px){.hero-scratchpad{transform:none;max-width:480px;margin:24px auto 0;}}

/* ---- Example equation cards (replace stock photos) ---- */
.example-cards{
  display:grid;grid-template-columns:repeat(4,1fr);gap:16px;
  max-width:920px;margin:30px auto 0;
}
@media (max-width:900px){.example-cards{grid-template-columns:repeat(2,1fr);}}
@media (max-width:520px){.example-cards{grid-template-columns:1fr;}}
.eq-card{
  border:none;text-align:left;cursor:pointer;border-radius:16px;padding:20px 18px;
  min-height:120px;display:flex;flex-direction:column;justify-content:flex-end;gap:8px;
  font-family:'Space Grotesk',sans-serif;transition:transform .15s ease,box-shadow .15s ease;
  box-shadow:var(--shadow);position:relative;
}
.eq-card:hover{transform:translateY(-3px);box-shadow:var(--shadow-lg);}
.eq-card .eq-card-tag{font-size:.72rem;text-transform:uppercase;letter-spacing:.06em;font-weight:700;opacity:.75;}
.eq-card .eq-card-expr{font-family:'JetBrains Mono',monospace;font-size:1.15rem;font-weight:700;}
.eq-card.c1{background:linear-gradient(155deg,#FDECD8,#F7DCB8);color:#7A4B10;}
.eq-card.c2{background:linear-gradient(155deg,#213050,#16213A);color:#F2D9A8;}
.eq-card.c3{background:linear-gradient(155deg,var(--jade-tint),#CFE9E2);color:var(--jade-dark);}
.eq-card.c4{background:linear-gradient(155deg,#FBE3E3,#F2C4C4);color:#8A2E2E;}

/* ---- Solver dock (chat-style input) ---- */
.solver-dock{
  --dock-bg:#121212;--dock-bg-raised:#1B1B1B;--dock-line:#2E2E2E;--dock-line-soft:#242424;
  --dock-border:#E9D9C0;--dock-text:#F4F2EC;--dock-text-soft:#9A9A9A;
  --dock-accent:#F0A63C;--dock-submit-bg:#8B5A14;
  max-width:920px;margin:30px auto 0;background:#0C0C0C;
  border-radius:24px;box-shadow:0 18px 50px rgba(12,12,12,.28),0 2px 0 rgba(232,163,61,.15) inset;
  padding:16px;position:relative;
}
.solver-dock::before{
  content:"";position:absolute;inset:-1px;border-radius:25px;padding:1px;
  background:linear-gradient(160deg,rgba(232,163,61,.55),rgba(232,163,61,0) 40%);
  -webkit-mask:linear-gradient(#fff 0 0) content-box,linear-gradient(#fff 0 0);
  -webkit-mask-composite:xor;mask-composite:exclude;pointer-events:none;
}
.dock-panel{
  background:var(--dock-bg);border:1.5px solid var(--dock-border);border-radius:34px;
  padding:22px 22px 14px;
}
.dock-textwrap{padding:0 6px 18px;position:relative;}
.dock-input{
  width:100%;border:none;outline:none;resize:none;background:transparent;
  font-family:'Space Grotesk',sans-serif;font-size:1.1rem;color:var(--dock-text);
  min-height:28px;line-height:1.5;padding-right:28px;
}
.dock-input::placeholder{color:#8A8A8A;}
.dock-input-clear{
  position:absolute;top:-2px;right:0;width:24px;height:24px;border-radius:50%;
  border:none;background:var(--dock-bg-raised);color:var(--dock-text-soft);cursor:pointer;
  display:flex;align-items:center;justify-content:center;font-size:.72rem;
}
.dock-input-clear:hover{color:var(--dock-text);background:var(--dock-line);}
.dock-toolbar{
  display:flex;align-items:center;gap:10px;flex-wrap:wrap;padding:0;
}
.dock-icon-btn{
  width:36px;height:36px;border-radius:9px;border:none;background:transparent;
  display:flex;align-items:center;justify-content:center;cursor:pointer;color:var(--dock-text);
  transition:background .15s ease,color .15s ease,border-color .15s ease;flex-shrink:0;
}
.dock-icon-btn svg{width:20px;height:20px;}
.dock-icon-btn.boxed{border:1.5px solid var(--dock-line);border-radius:10px;}
.dock-icon-btn.sigma-btn{font-family:'JetBrains Mono',monospace;font-size:1.05rem;font-weight:600;}
.dock-icon-btn:hover{background:var(--dock-bg-raised);color:var(--dock-accent);}
.dock-icon-btn.recording{background:var(--coral);border-color:var(--coral);color:#fff;}
.dock-toggle{
  display:flex;align-items:center;background:transparent;border:1.5px solid var(--dock-line);border-radius:100px;padding:4px;gap:2px;
}
.dock-toggle button{
  display:flex;align-items:center;gap:6px;border:1.5px solid transparent;background:transparent;padding:7px 16px;border-radius:100px;font-size:.92rem;
  font-weight:600;color:var(--dock-text-soft);cursor:pointer;font-family:'Space Grotesk',sans-serif;
}
.dock-toggle button svg{width:16px;height:16px;}
.dock-toggle button[aria-pressed="true"]{background:rgba(240,166,60,.1);color:var(--dock-accent);border-color:var(--dock-accent);}
.dock-select-wrap{display:flex;position:relative;align-items:center;}
.dock-select-icon{position:absolute;left:14px;pointer-events:none;color:var(--dock-text);display:flex;}
.dock-select-icon svg{width:17px;height:17px;}
.dock-select{
  appearance:none;-webkit-appearance:none;background:transparent url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="%239A9A9A" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="m6 9 6 6 6-6"/></svg>') no-repeat right 14px center/14px;
  border:1.5px solid var(--dock-line);color:var(--dock-text);border-radius:100px;
  padding:9px 34px 9px 40px;font-size:.92rem;font-weight:600;font-family:'Space Grotesk',sans-serif;
  cursor:pointer;max-width:210px;
}
.dock-select:hover{border-color:var(--dock-accent);}
.dock-spacer{flex:1;}
.dock-submit{
  width:44px;height:44px;border-radius:50%;background:var(--dock-submit-bg);color:var(--dock-text-soft);border:none;
  display:flex;align-items:center;justify-content:center;cursor:pointer;flex-shrink:0;
  transition:background .15s ease,transform .15s ease;
}
.dock-submit svg{width:20px;height:20px;}
.dock-submit:hover{background:#A0680E;transform:scale(1.05);}
[hidden]{display:none!important;}
.symbol-popover,.calc-popover{
  position:absolute;background:var(--dock-bg-raised);border:1px solid var(--dock-line);border-radius:12px;
  box-shadow:var(--shadow-lg);padding:8px;display:grid;grid-template-columns:repeat(4,1fr);gap:6px;
  z-index:50;margin-top:8px;bottom:100%;
}
.symbol-popover button,.calc-popover button{
  font-family:'JetBrains Mono',monospace;border:none;background:var(--dock-bg);border-radius:8px;
  padding:9px 0;cursor:pointer;font-size:1rem;color:var(--dock-text);
}
.symbol-popover button:hover,.calc-popover button:hover{background:rgba(240,166,60,.14);color:var(--dock-accent);}
.calc-popover button.op{color:var(--dock-accent);}
.dock-hint{font-size:.78rem;color:var(--dock-text-soft);padding:14px 6px 2px;}
.ocr-status{font-size:.78rem;color:var(--dock-accent);padding:0 6px 10px;margin:0;}
.dock-icon-btn.processing{position:relative;color:transparent!important;}
.dock-icon-btn.processing svg{visibility:hidden;}
.dock-icon-btn.processing::after{
  content:"";position:absolute;inset:0;margin:auto;width:16px;height:16px;
  border:2px solid var(--dock-line);border-top-color:var(--dock-accent);
  border-radius:50%;animation:dock-spin .7s linear infinite;
}
@keyframes dock-spin{to{transform:rotate(360deg);}}
.dock-chips{display:flex;flex-wrap:wrap;gap:8px;padding:12px 4px 2px;justify-content:center;}

/* ---- Live formatted preview of what's being typed ---- */
.dock-preview{
  min-height:1.1em;padding:2px 2px 0;font-size:.98rem;color:var(--dock-accent);
  letter-spacing:.01em;opacity:0;transform:translateY(-2px);transition:opacity .15s ease,transform .15s ease;
}
.dock-preview.show{opacity:1;transform:translateY(0);}
.dock-preview sup{font-size:.68em;position:relative;top:-.5em;}

/* ==============================================================
   Dark-theme overrides — the result area below the dark solver
   dock (homepage) reuses the shared .solution-panel/.step/etc.
   markup, but needs dock-matched colors instead of the page's
   light palette so it doesn't look like a mismatched light card
   dropped onto a black panel.
   ============================================================== */
.solver-dock .solution-panel,
.solver-dock .solver-error,
.solver-dock .solve-history{margin-left:12px;margin-right:12px;}
.solver-dock .solution-panel{border-top-color:var(--dock-line);}
.solver-dock .solution-answer{background:var(--dock-bg-raised);border:1px solid var(--dock-line);}
.solver-dock .solution-answer .label{color:var(--dock-accent);}
.solver-dock .solution-answer .value{color:var(--dock-text);}
.solver-dock .verified-note{color:#7FE3B4;}
.solver-dock .step{border-bottom-color:var(--dock-line-soft);}
.solver-dock .step-num{background:var(--dock-accent);color:#241804;}
.solver-dock .step-body .step-title{color:var(--dock-text-soft);}
.solver-dock .step-body .step-expr{color:var(--dock-text);}
.solver-dock .step-note{background:rgba(240,166,60,.09);border-left-color:var(--dock-accent);color:var(--dock-text-soft);}
.solver-dock #explainBtn[aria-pressed="true"],
.solver-dock #stepThroughBtn[aria-pressed="true"]{background:var(--dock-accent);color:#241804;border-color:var(--dock-accent);}
.solver-dock .btn-ghost{background:transparent;color:var(--dock-text);border:1.5px solid var(--dock-line);}
.solver-dock .btn-ghost:hover{border-color:var(--dock-accent);color:var(--dock-accent);}
.solver-dock .solver-error{background:rgba(225,85,58,.14);color:#FF9B85;border:1px solid rgba(225,85,58,.4);}
.solver-dock .number-line-wrap{
  background:var(--dock-bg-raised);border:1px solid var(--dock-line);
  --line:var(--dock-line);--ink-soft:var(--dock-text-soft);--jade:var(--dock-accent);--paper:var(--dock-bg-raised);
}
.solver-dock .number-line-wrap .nl-caption{color:var(--dock-text-soft);}
.solver-dock .solve-history{margin-top:10px;}

/* ---- Step-through stepper ---- */
.step-stepper{display:flex;align-items:center;gap:10px;margin-top:14px;padding-top:14px;border-top:1px dashed var(--dock-line);}
.solution-panel:not(.step-mode) .step-stepper{display:none;}
.solution-panel.step-mode #stepsList .step{display:none;}
.solution-panel.step-mode #stepsList .step.step-current{display:grid;}
.step-stepper button{
  width:34px;height:34px;border-radius:50%;border:1.5px solid var(--dock-line);background:transparent;
  color:var(--dock-text);cursor:pointer;display:flex;align-items:center;justify-content:center;font-size:.95rem;
}
.step-stepper button:hover:not(:disabled){border-color:var(--dock-accent);color:var(--dock-accent);}
.step-stepper button:disabled{opacity:.35;cursor:not-allowed;}
.step-stepper .step-counter{font-family:'JetBrains Mono',monospace;font-size:.85rem;color:var(--dock-text-soft);}

/* ---- Mini graph preview + link to full grapher ---- */
.graph-preview-wrap{
  background:var(--dock-bg-raised);border:1px solid var(--dock-line);border-radius:var(--radius-sm);
  padding:14px 14px 10px;margin-bottom:16px;
}
.graph-preview-wrap .gp-caption{
  display:flex;align-items:center;justify-content:space-between;gap:10px;
  font-size:.75rem;text-transform:uppercase;letter-spacing:.06em;color:var(--dock-text-soft);padding-bottom:8px;
}
.graph-preview-wrap .gp-caption a{
  text-transform:none;letter-spacing:0;color:var(--dock-accent);text-decoration:none;font-weight:600;font-size:.82rem;
  display:inline-flex;align-items:center;gap:4px;
}
.graph-preview-wrap .gp-caption a:hover{text-decoration:underline;}
.graph-preview-wrap svg{display:block;width:100%;height:auto;}

/* ---- Practice-similar chips (dark) ---- */
.similar-practice{margin-top:16px;}
.similar-practice .sp-label{
  font-size:.75rem;text-transform:uppercase;letter-spacing:.06em;color:var(--dock-text-soft);
  margin-bottom:8px;
}
.dock-chip{
  font-family:'JetBrains Mono',monospace;font-size:.82rem;background:var(--dock-bg-raised);color:var(--dock-accent);
  border:1px solid var(--dock-line);padding:7px 12px;border-radius:100px;cursor:pointer;margin:0 8px 8px 0;
  transition:border-color .15s ease,background .15s ease;
}
.dock-chip:hover{border-color:var(--dock-accent);background:rgba(240,166,60,.08);}
.dock-chip:before{content:"try  ";opacity:.55;}

@media (max-width:820px){
  .app-sidebar{
    position:fixed;left:0;top:0;bottom:0;z-index:110;transform:translateX(-100%);
    transition:transform .25s ease;width:250px;
  }
  .app-sidebar.open{transform:translateX(0);box-shadow:var(--shadow-lg);}
  .sidebar-close{display:block;}
  .mobile-menu-btn{display:flex;align-items:center;justify-content:center;}
  .app-main{padding:0 16px 50px;}
  .app-topbar{padding-left:52px;}
  .app-topbar-links{display:none;}
  .hero-stage{margin:0 -16px 4px;padding:28px 0 34px;}
  .hero-stage-inner{padding:0 16px;}
  .hero-stage::before,.hero-stage::after{width:260px;height:260px;filter:blur(40px);}
  .app-footer-top{grid-template-columns:1fr 1fr;}
}
@media (max-width:500px){
  .solver-dock{border-radius:20px;padding:10px;}
  .dock-panel{border-radius:26px;padding:16px 14px 12px;}
  .dock-toolbar{padding-top:0;}
  .dock-icon-btn{width:38px;height:38px;}
  .dock-submit{width:44px;height:44px;}
  .dock-select{max-width:135px;font-size:.78rem;padding:8px 26px 8px 34px;}
  .dock-select-icon{left:10px;}
  .dock-toggle button{padding:7px 10px;font-size:.78rem;}
  .stats-bar{gap:8px;}
  .stat-pill{font-size:.76rem;padding:7px 11px;}
  .tool-tab{padding:9px 14px;font-size:.86rem;}
  .hero-kicker{font-size:.72rem;flex-wrap:wrap;}
  .faq-item summary{padding:14px 26px 14px 0;font-size:.98rem;}
  .faq-item p{padding:0 26px 14px 0;}
  .cheat-card{padding:6px 14px 2px;}
}

/* ---------- Worked-example cards (rich static content, no JS needed) ---------- */
.worked-example{
  background:var(--white);border:1px solid var(--line);border-radius:var(--radius);
  padding:22px 24px;margin-top:18px;
}
.worked-example + .worked-example{margin-top:14px;}
.worked-example-head{
  display:flex;align-items:center;justify-content:space-between;gap:12px;flex-wrap:wrap;margin-bottom:10px;
}
.worked-example-head h3{margin:0;font-size:1.05rem;}
.worked-example-tag{
  font-family:'JetBrains Mono',monospace;font-size:.82rem;color:var(--jade-dark);
  background:var(--jade-tint);padding:3px 10px;border-radius:100px;
}
.worked-example ol{margin:10px 0 12px;padding-left:22px;}
.worked-example ol li{margin-bottom:6px;line-height:1.55;}
.worked-example .we-answer{
  font-family:'JetBrains Mono',monospace;font-weight:700;color:var(--ink);
  background:var(--paper-dim);border-radius:8px;padding:8px 12px;display:inline-block;margin-top:4px;
}
.breadcrumb-nav{font-size:.82rem;color:var(--ink-soft);margin:14px 0 0;}
.breadcrumb-nav a{color:var(--ink-soft);}
.breadcrumb-nav a:hover{color:var(--jade-dark);}

/* =========================================================
   Homepage — trust bar & tool picker (competitor-style tabs)
   ========================================================= */
.stats-bar{
  display:flex;flex-wrap:wrap;justify-content:center;gap:10px;
  max-width:920px;margin:22px auto 0;
}
.stat-pill{
  display:flex;align-items:center;gap:7px;background:var(--white);
  border:1px solid var(--line);border-radius:100px;padding:8px 14px;
  font-size:.82rem;color:var(--ink-soft);font-weight:500;white-space:nowrap;
}
.stat-ic{font-size:.95rem;line-height:1;}

.tool-picker{
  display:flex;flex-wrap:nowrap;gap:8px;overflow-x:auto;-webkit-overflow-scrolling:touch;
  max-width:920px;margin:20px auto 0;padding:4px 4px 10px;
  scrollbar-width:thin;
}
.tool-picker::-webkit-scrollbar{height:6px;}
.tool-picker::-webkit-scrollbar-thumb{background:var(--line);border-radius:100px;}
.tool-tab{
  display:flex;align-items:center;gap:8px;flex-shrink:0;
  background:var(--white);border:1.5px solid var(--line);border-radius:100px;
  padding:10px 18px;font-size:.92rem;font-weight:600;color:var(--ink-soft);
  text-decoration:none;transition:border-color .15s ease,color .15s ease,background .15s ease,transform .15s ease;
  min-height:44px;
}
.tool-tab:hover{border-color:var(--jade);color:var(--jade-dark);transform:translateY(-1px);}
.tool-tab.active{background:var(--ink);border-color:var(--ink);color:var(--paper);}
.tt-ic{font-family:'JetBrains Mono',monospace;font-weight:700;display:inline-flex;width:18px;justify-content:center;}
.tt-badge{
  background:var(--coral);color:#fff;font-size:.62rem;font-weight:700;letter-spacing:.03em;
  text-transform:uppercase;padding:2px 6px;border-radius:100px;
}

.sidebar-badge{
  margin-left:auto;background:var(--coral);color:#fff;font-size:.62rem;font-weight:700;
  letter-spacing:.03em;text-transform:uppercase;padding:2px 6px;border-radius:100px;
}

/* ---- Bigger clickable tool cards ("What it solves") ---- */
.tool-card{
  text-decoration:none;color:inherit;display:flex;flex-direction:column;
  transition:transform .18s ease,box-shadow .18s ease,border-color .18s ease;
  position:relative;overflow:hidden;
}
.tool-card:hover{transform:translateY(-4px);box-shadow:var(--shadow-lg);border-color:var(--jade);}
.tool-card-ic{
  width:44px;height:44px;border-radius:12px;background:var(--jade-tint);color:var(--jade-dark);
  display:flex;align-items:center;justify-content:center;font-family:'JetBrains Mono',monospace;
  font-weight:700;font-size:1.1rem;margin-bottom:14px;
}
.tool-card-link{color:var(--jade-dark);font-weight:600;font-size:.92rem;margin-top:auto;padding-top:6px;}

/* ---------- Horizontal scroll wrapper for wide tables on small screens ---------- */
.cheat-card{
  background:var(--white);border:1px solid var(--line);border-radius:var(--radius);
  padding:8px 20px 4px;box-shadow:var(--shadow);
}
.table-scroll{overflow-x:auto;-webkit-overflow-scrolling:touch;margin-top:10px;}
.table-scroll .syntax-table{margin-top:0;min-width:560px;}

/* =========================================================
   App-shell footer (multi-column, matches the rest of the workspace)
   ========================================================= */
.app-footer{
  margin-top:32px;background:var(--ink);color:#B9C1D4;border-radius:22px;
  padding:44px 40px 26px;
}
.app-footer-top{display:grid;grid-template-columns:1.6fr 1fr 1fr 1fr;gap:32px;}
.app-footer-brand{display:flex;flex-direction:column;gap:12px;}
.app-footer-brand .brand{color:#fff;}
.app-footer-brand .brand-name{color:#fff;}
.app-footer-brand .brand-name span{color:var(--amber);}
.app-footer-brand p{color:#8993AC;font-size:.9rem;max-width:280px;margin:0;}
.app-footer h4{
  color:#fff;font-family:'Space Grotesk',sans-serif;font-size:.78rem;
  text-transform:uppercase;letter-spacing:.07em;margin:0 0 14px;
}
.app-footer-links{list-style:none;padding:0;margin:0;display:flex;flex-direction:column;gap:10px;}
.app-footer-links a{color:#B9C1D4;text-decoration:none;font-size:.92rem;}
.app-footer-links a:hover{color:var(--amber);}
.app-footer-bottom{
  border-top:1px solid #2A3555;margin-top:34px;padding-top:20px;
  display:flex;justify-content:space-between;flex-wrap:wrap;gap:10px;font-size:.82rem;color:#8993AC;
}
.app-footer-bottom a{color:#8993AC;text-decoration:none;}
.app-footer-bottom a:hover{color:#fff;}
@media (max-width:820px){
  .app-footer-top{grid-template-columns:1fr 1fr;}
  .app-footer-brand{grid-column:1 / -1;}
}
@media (max-width:520px){
  .app-footer{padding:32px 22px 22px;border-radius:18px;}
  .app-footer-top{grid-template-columns:1fr 1fr;gap:26px;}
}

/* =========================================================
   Graphing calculator page
   ========================================================= */
.grapher-card{
  background:var(--white);border:1px solid var(--line);border-radius:var(--radius);
  box-shadow:var(--shadow-lg);padding:22px;margin-top:24px;
}
.grapher-controls{display:flex;gap:10px;flex-wrap:wrap;align-items:center;margin-bottom:16px;}
.grapher-controls .solver-input{flex:1 1 260px;font-size:1.05rem;padding:13px 16px;}
.grapher-canvas-wrap{
  position:relative;width:100%;background:#fff;border:1px solid var(--line);
  border-radius:var(--radius-sm);overflow:hidden;touch-action:none;
}
#graphCanvas{display:block;width:100%;height:420px;cursor:grab;}
#graphCanvas:active{cursor:grabbing;}
.grapher-toolbar{display:flex;gap:8px;flex-wrap:wrap;margin-top:12px;align-items:center;justify-content:space-between;}
.grapher-zoom{display:flex;gap:6px;}
.grapher-presets{display:flex;flex-wrap:wrap;gap:8px;margin-top:14px;}
.grapher-error{
  background:#FBEAE5;color:#9A3421;border:1px solid #F2C7BA;border-radius:var(--radius-sm);
  padding:10px 14px;margin-top:12px;font-size:.88rem;
}
.function-swatch{width:12px;height:12px;border-radius:3px;flex-shrink:0;}
@media (max-width:600px){
  #graphCanvas{height:320px;}
  .grapher-card{padding:16px;}
}

/* =========================================================
   Practice mode page
   ========================================================= */
.practice-card{
  background:var(--white);border:1px solid var(--line);border-radius:var(--radius);
  box-shadow:var(--shadow-lg);padding:28px;margin-top:24px;max-width:760px;margin-left:auto;margin-right:auto;
}
.practice-topics{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:20px;}
.practice-topic-btn{
  border:1.5px solid var(--line);background:var(--white);border-radius:100px;padding:9px 16px;
  font-size:.85rem;font-weight:600;color:var(--ink-soft);cursor:pointer;
  font-family:'Space Grotesk',sans-serif;transition:all .15s ease;min-height:40px;
}
.practice-topic-btn[aria-pressed="true"]{background:var(--ink);border-color:var(--ink);color:var(--paper);}
.practice-scoreboard{
  display:flex;gap:18px;flex-wrap:wrap;background:var(--paper-dim);border-radius:var(--radius-sm);
  padding:14px 18px;margin-bottom:20px;
}
.score-item{display:flex;flex-direction:column;}
.score-item .n{font-family:'Fraunces',serif;font-size:1.5rem;font-weight:700;color:var(--ink);}
.score-item .l{font-size:.72rem;text-transform:uppercase;letter-spacing:.06em;color:var(--ink-soft);}
.practice-problem{
  text-align:center;padding:28px 16px;background:var(--jade-tint);border-radius:var(--radius-sm);
  margin-bottom:18px;
}
.practice-problem-label{font-size:.75rem;text-transform:uppercase;letter-spacing:.06em;color:var(--jade-dark);font-weight:700;margin-bottom:10px;}
.practice-problem-expr{font-family:'JetBrains Mono',monospace;font-size:1.6rem;font-weight:700;color:var(--ink);word-break:break-word;}
.practice-answer-row{display:flex;gap:10px;flex-wrap:wrap;margin-bottom:8px;}
.practice-answer-row .solver-input{flex:1 1 200px;}
.practice-feedback{border-radius:var(--radius-sm);padding:14px 16px;margin-top:14px;font-size:.92rem;display:none;}
.practice-feedback.show{display:block;}
.practice-feedback.correct{background:var(--jade-tint);color:var(--jade-dark);border:1px solid #BEE0D8;}
.practice-feedback.incorrect{background:#FBEAE5;color:#9A3421;border:1px solid #F2C7BA;}
.practice-feedback .pf-answer{font-family:'JetBrains Mono',monospace;font-weight:700;}
.practice-solution{margin-top:16px;}
@media (max-width:600px){
  .practice-card{padding:18px;}
  .practice-problem-expr{font-size:1.3rem;}
}

/* =========================================================
   Nav — accommodate two extra top-level links without wrapping
   ========================================================= */
.main-nav{gap:16px;}
.main-nav a{font-size:.9rem;}
@media (max-width:1180px) and (min-width:821px){
  .main-nav{gap:11px;}
  .main-nav a{font-size:.82rem;}
  .nav-cta{padding:9px 14px !important;}
}

/* =========================================================
   Practice Tests (/tools/practicetest/)
   ========================================================= */
.test-card{
  background:var(--white);border:1px solid var(--line);border-radius:var(--radius);
  padding:24px;display:flex;flex-direction:column;gap:10px;
}
.test-card-top{display:flex;align-items:flex-start;justify-content:space-between;gap:10px;}
.test-card h3{margin-bottom:0;}
.test-meta{display:flex;gap:14px;flex-wrap:wrap;font-size:.82rem;color:var(--ink-soft);margin:2px 0 4px;}
.test-best{
  font-size:.76rem;color:var(--jade-dark);background:var(--jade-tint);
  padding:4px 10px;border-radius:100px;display:inline-block;font-weight:600;white-space:nowrap;
}
.test-runner-top{
  display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:10px;
  max-width:760px;margin:0 auto 10px;padding:0 4px;
}
.test-runner-top h2{margin-bottom:0;font-size:1.1rem;}
.test-runner-meta{display:flex;align-items:center;gap:14px;font-size:.9rem;color:var(--ink-soft);}
.test-timer{
  font-family:'JetBrains Mono',monospace;font-weight:700;color:var(--ink);
  background:var(--paper-dim);border-radius:100px;padding:5px 12px;
}
.test-progress-track{
  max-width:760px;margin:0 auto 22px;height:8px;background:var(--paper-dim);
  border-radius:100px;overflow:hidden;
}
.test-progress-fill{height:100%;background:var(--jade);border-radius:100px;transition:width .3s ease;}
.q-kind-tag{
  font-size:.72rem;text-transform:uppercase;letter-spacing:.05em;font-weight:700;
  color:var(--coral);display:block;margin-top:4px;
}
.frq-mark-row{display:flex;gap:10px;flex-wrap:wrap;margin-top:16px;}
.test-results-card{
  background:var(--white);border:1px solid var(--line);border-radius:var(--radius);
  box-shadow:var(--shadow-lg);padding:34px 28px;margin:24px auto;max-width:760px;text-align:center;
}
.results-score{font-family:'Fraunces',serif;font-size:3rem;font-weight:700;color:var(--ink);line-height:1;margin:6px 0;}
.results-stats{display:flex;gap:26px;justify-content:center;flex-wrap:wrap;margin:14px 0 6px;}
.results-stats .rs-item .n{font-family:'JetBrains Mono',monospace;font-weight:700;font-size:1.15rem;color:var(--jade-dark);display:block;}
.results-stats .rs-item .l{font-size:.75rem;text-transform:uppercase;letter-spacing:.05em;color:var(--ink-soft);}
.results-review{max-width:760px;margin:0 auto;text-align:left;}
@media (max-width:600px){
  .test-card{padding:18px;}
  .results-score{font-size:2.3rem;}
}

/* =========================================================
   AP Exam Hub (/ap-exams/)
   ========================================================= */
.ap-course-card{
  background:var(--white);border:1px solid var(--line);border-radius:var(--radius);padding:24px;
  display:flex;flex-direction:column;gap:10px;
}
.ap-course-tag{
  align-self:flex-start;font-size:.72rem;font-weight:700;text-transform:uppercase;letter-spacing:.05em;
  padding:4px 10px;border-radius:100px;background:var(--jade-tint);color:var(--jade-dark);
}
.ap-course-tag.soon{background:#FDECD8;color:#9A5B0E;}
.ap-topic-list{list-style:none;padding:0;margin:2px 0 4px;display:flex;flex-direction:column;gap:6px;}
.ap-topic-list li{font-size:.9rem;color:var(--ink-soft);padding-left:16px;position:relative;}
.ap-topic-list li::before{content:"—";position:absolute;left:0;color:var(--jade);}
.ap-score-row{display:flex;gap:8px;flex-wrap:wrap;margin-top:14px;}
.ap-score-chip{
  flex:1 1 60px;text-align:center;padding:10px 6px;border-radius:var(--radius-sm);
  background:var(--paper-dim);font-family:'JetBrains Mono',monospace;font-weight:700;
}
.ap-score-chip small{display:block;font-family:'Space Grotesk',sans-serif;font-weight:500;font-size:.68rem;color:var(--ink-soft);margin-top:2px;}