/* ===================================================================
   MATH.LAB — shared stylesheet
   Palette: blackboard navy / chalk white / chalk gold / chalk cyan
   =================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Fraunces:opsz,wght@9..144,400;9..144,600;9..144,700&family=Work+Sans:wght@400;500;600&family=IBM+Plex+Mono:wght@400;500;600&display=swap');

:root {
  --navy: #0B1D26;
  --navy-deep: #071319;
  --grid-line: #1C3540;
  --chalk: #F4EDE2;
  --chalk-dim: #C9C2B6;
  --gold: #E8B65A;
  --gold-dim: #B8905F;
  --cyan: #6FC2C0;
  --rose: #D98770;

  --serif: 'Fraunces', Georgia, serif;
  --sans: 'Work Sans', -apple-system, sans-serif;
  --mono: 'IBM Plex Mono', 'Courier New', monospace;

  --radius: 6px;
  --border: 1px solid var(--grid-line);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--navy);
  background-image:
    linear-gradient(var(--grid-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-line) 1px, transparent 1px);
  background-size: 42px 42px;
  background-attachment: fixed;
  color: var(--chalk);
  font-family: var(--sans);
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }

h1, h2, h3 { font-family: var(--serif); font-weight: 600; margin: 0 0 0.4em; letter-spacing: -0.01em; }
h1 { font-size: clamp(2.2rem, 5vw, 3.4rem); font-weight: 700; }
h2 { font-size: clamp(1.5rem, 3vw, 2rem); }
h3 { font-size: 1.15rem; }

p { color: var(--chalk-dim); margin: 0 0 1em; }

.mono { font-family: var(--mono); }

::selection { background: var(--gold); color: var(--navy-deep); }

/* ---------- layout shell ---------- */
.wrap {
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 32px;
}

/* ---------- navbar ---------- */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(11, 29, 38, 0.92);
  backdrop-filter: blur(8px);
  border-bottom: var(--border);
}
.navbar .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
}
.brand {
  font-family: var(--serif);
  font-weight: 700;
  font-size: 1.3rem;
  color: var(--chalk);
  display: flex;
  align-items: baseline;
  gap: 2px;
}
.brand .dot { color: var(--gold); }
.nav-links {
  display: flex;
  gap: 4px;
  list-style: none;
  margin: 0;
  padding: 0;
}
.nav-links a {
  display: inline-block;
  padding: 8px 16px;
  border-radius: var(--radius);
  font-size: 0.92rem;
  font-weight: 500;
  color: var(--chalk-dim);
  transition: color 0.15s, background 0.15s;
}
.nav-links a:hover { color: var(--chalk); background: rgba(244,237,226,0.06); }
.nav-links a.active { color: var(--gold); background: rgba(232,182,90,0.09); }
.nav-toggle { display: none; }

@media (max-width: 780px) {
  .nav-links { display: none; }
  .nav-toggle {
    display: block;
    background: none;
    border: var(--border);
    color: var(--chalk);
    padding: 6px 12px;
    border-radius: var(--radius);
    font-family: var(--mono);
    font-size: 0.85rem;
  }
  .nav-links.open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 68px; left: 0; right: 0;
    background: var(--navy);
    border-bottom: var(--border);
    padding: 10px 20px 20px;
  }
}

/* ---------- hero ---------- */
.hero {
  padding: 88px 0 64px;
}
.hero .wrap {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 56px;
  align-items: center;
}
.eyebrow {
  font-family: var(--mono);
  font-size: 0.78rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--cyan);
  margin-bottom: 18px;
  display: block;
}
.hero-copy p.lead {
  font-size: 1.08rem;
  color: var(--chalk-dim);
  max-width: 46ch;
}
.cta-row { display: flex; gap: 12px; margin-top: 28px; flex-wrap: wrap; }
.btn {
  font-family: var(--sans);
  font-weight: 600;
  font-size: 0.92rem;
  padding: 12px 22px;
  border-radius: var(--radius);
  border: var(--border);
  cursor: pointer;
  transition: transform 0.12s, background 0.15s, border-color 0.15s;
  display: inline-block;
}
.btn-primary { background: var(--gold); color: var(--navy-deep); border-color: var(--gold); }
.btn-primary:hover { transform: translateY(-1px); background: #f0c375; }
.btn-ghost { background: transparent; color: var(--chalk); }
.btn-ghost:hover { border-color: var(--chalk-dim); }

.hero-visual {
  background: var(--navy-deep);
  border: var(--border);
  border-radius: 10px;
  padding: 18px;
  position: relative;
}
.hero-visual canvas { width: 100%; height: auto; display: block; }
.hero-visual .caption {
  font-family: var(--mono);
  font-size: 0.76rem;
  color: var(--chalk-dim);
  display: flex;
  justify-content: space-between;
  margin-top: 12px;
}
.hero-visual .caption .n { color: var(--gold); }

/* ---------- topic cards ---------- */
.topics { padding: 40px 0 96px; }
.topics .section-head { margin-bottom: 32px; max-width: 60ch; }
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 18px;
}
.card {
  border: var(--border);
  border-radius: 10px;
  padding: 24px;
  background: rgba(244,237,226,0.02);
  transition: border-color 0.15s, background 0.15s, transform 0.15s;
  display: block;
}
.card:hover {
  border-color: var(--gold-dim);
  background: rgba(232,182,90,0.05);
  transform: translateY(-2px);
}
.card .glyph {
  font-family: var(--serif);
  font-size: 1.8rem;
  color: var(--gold);
  margin-bottom: 14px;
  display: block;
}
.card h3 { margin-bottom: 6px; }
.card p { font-size: 0.9rem; margin: 0; }

/* ---------- footer ---------- */
footer {
  border-top: var(--border);
  padding: 28px 0;
}
footer .wrap {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--chalk-dim);
  flex-wrap: wrap;
  gap: 8px;
}

/* ===================================================================
   Inner concept pages (trig / shapes / integration / differentiation)
   =================================================================== */
.page-head { padding: 56px 0 8px; }
.page-head .eyebrow { margin-bottom: 12px; }
.page-head p.lead { max-width: 62ch; }

.subnav {
  border-bottom: var(--border);
  margin: 28px 0 0;
}
.subnav .wrap { display: flex; gap: 4px; overflow-x: auto; }
.subnav button {
  background: none;
  border: none;
  color: var(--chalk-dim);
  font-family: var(--sans);
  font-weight: 500;
  font-size: 0.92rem;
  padding: 12px 18px;
  cursor: pointer;
  border-bottom: 2px solid transparent;
  white-space: nowrap;
  transition: color 0.15s, border-color 0.15s;
}
.subnav button:hover { color: var(--chalk); }
.subnav button.active { color: var(--gold); border-bottom-color: var(--gold); }

.stage {
  padding: 36px 0 96px;
}
.stage-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 32px;
  align-items: start;
}
@media (max-width: 860px) {
  .stage-grid { grid-template-columns: 1fr; }
  .hero .wrap { grid-template-columns: 1fr; }
}

.panel {
  border: var(--border);
  border-radius: 10px;
  background: rgba(244,237,226,0.02);
  padding: 22px;
}
.panel canvas { width: 100%; height: auto; display: block; background: var(--navy-deep); border-radius: 6px; }

.controls { display: flex; flex-direction: column; gap: 18px; margin-top: 18px; }
.control-row { display: flex; flex-direction: column; gap: 6px; }
.control-row label {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--cyan);
  display: flex;
  justify-content: space-between;
}
input[type="range"] {
  -webkit-appearance: none;
  width: 100%;
  height: 4px;
  background: var(--grid-line);
  border-radius: 2px;
  outline: none;
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 16px; height: 16px;
  border-radius: 50%;
  background: var(--gold);
  cursor: pointer;
  border: 2px solid var(--navy-deep);
}
input[type="range"]::-moz-range-thumb {
  width: 16px; height: 16px;
  border-radius: 50%;
  background: var(--gold);
  cursor: pointer;
  border: 2px solid var(--navy-deep);
}
select {
  background: var(--navy-deep);
  color: var(--chalk);
  border: var(--border);
  border-radius: var(--radius);
  padding: 9px 12px;
  font-family: var(--mono);
  font-size: 0.85rem;
}
.chip-row { display: flex; gap: 8px; flex-wrap: wrap; }
.chip {
  border: var(--border);
  background: transparent;
  color: var(--chalk-dim);
  padding: 7px 14px;
  border-radius: 20px;
  font-family: var(--mono);
  font-size: 0.8rem;
  cursor: pointer;
  transition: all 0.15s;
}
.chip.active { background: var(--gold); color: var(--navy-deep); border-color: var(--gold); font-weight: 600; }
.chip:hover:not(.active) { border-color: var(--chalk-dim); color: var(--chalk); }

.readout {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 10px;
  margin-top: 18px;
}
.readout .stat {
  border: var(--border);
  border-radius: 8px;
  padding: 12px 14px;
  background: var(--navy-deep);
}
.readout .stat .k { font-family: var(--mono); font-size: 0.72rem; color: var(--chalk-dim); text-transform: uppercase; letter-spacing: 0.06em; }
.readout .stat .v { font-family: var(--mono); font-size: 1.25rem; color: var(--gold); margin-top: 4px; }

.content-block { margin-top: 8px; }
.content-block h3 { color: var(--chalk); margin-top: 22px; }
.formula {
  font-family: var(--mono);
  background: var(--navy-deep);
  border: var(--border);
  border-radius: 8px;
  padding: 14px 18px;
  color: var(--cyan);
  font-size: 1.05rem;
  margin: 10px 0;
  overflow-x: auto;
}

/* ---------- data table (synthetic division etc.) ---------- */
.data-table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--mono);
  font-size: 0.92rem;
  margin: 14px 0;
  overflow-x: auto;
  display: block;
}
.data-table table { width: 100%; border-collapse: collapse; }
.data-table th, .data-table td {
  border: var(--border);
  padding: 9px 12px;
  text-align: center;
  color: var(--chalk);
}
.data-table th {
  background: rgba(232,182,90,0.08);
  color: var(--gold);
  font-weight: 600;
}
.data-table td.dim { color: var(--chalk-dim); }
.data-table td.result { color: var(--cyan); font-weight: 600; }

/* ---------- text inputs (for polynomial coefficients etc.) ---------- */
.text-input {
  background: var(--navy-deep);
  color: var(--chalk);
  border: var(--border);
  border-radius: var(--radius);
  padding: 9px 12px;
  font-family: var(--mono);
  font-size: 0.9rem;
  width: 100%;
}
.text-input:focus { outline: none; border-color: var(--gold-dim); }
.hint { font-size: 0.78rem; color: var(--chalk-dim); margin-top: 4px; }
.error-msg { color: var(--rose); font-size: 0.85rem; margin-top: 8px; }

/* ---------- timeline (history-style pages) ---------- */
.timeline {
  display: grid;
  gap: 0;
  border-left: 2px solid var(--grid-line);
  padding-left: 28px;
  margin: 18px 0 0 6px;
}
.timeline-item { position: relative; padding-bottom: 26px; }
.timeline-item:last-child { padding-bottom: 0; }
.timeline-item::before {
  content: '';
  position: absolute;
  left: -33px;
  top: 4px;
  width: 10px; height: 10px;
  border-radius: 50%;
  background: var(--gold);
  box-shadow: 0 0 0 3px var(--navy-deep);
}
.timeline-date {
  font-family: var(--mono);
  color: var(--cyan);
  font-size: 0.85rem;
  margin-bottom: 4px;
}
.timeline-title { font-weight: 600; color: var(--chalk); margin-bottom: 4px; font-family: var(--sans); }
.timeline-desc { color: var(--chalk-dim); font-size: 0.94rem; margin: 0; }

/* ---------- reusable step label (e.g. "// 01") for card grids ---------- */
.step-label {
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--gold);
  display: block;
  margin-bottom: 8px;
}

/* ---------- proof / toggle step list ---------- */
.proof-grid {
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: 28px;
  align-items: start;
}
@media (max-width: 800px) { .proof-grid { grid-template-columns: 1fr; } }
.proof-steps { display: flex; flex-direction: column; gap: 14px; }
.proof-step { display: flex; gap: 14px; align-items: flex-start; }
.proof-step-num {
  flex-shrink: 0;
  width: 28px; height: 28px;
  border-radius: 50%;
  background: var(--navy);
  border: var(--border);
  display: flex; align-items: center; justify-content: center;
  font-family: var(--mono);
  font-size: 0.82rem;
  color: var(--gold);
}
.proof-step p { font-size: 0.92rem; margin: 0; color: var(--chalk-dim); }
.proof-step .math { color: var(--cyan); font-family: var(--mono); }
.mini-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
  margin-top: 18px;
}
.mini-grid .card .step {
  font-family: var(--mono);
  font-size: 0.75rem;
  color: var(--cyan);
  display: block;
  margin-bottom: 10px;
}

/* ---------- timeline (history-style content) ---------- */
.timeline {
  border-left: 2px solid var(--grid-line);
  padding-left: 28px;
  margin-left: 6px;
  margin-top: 22px;
}
.timeline-item { position: relative; padding-bottom: 26px; }
.timeline-item:last-child { padding-bottom: 0; }
.timeline-item::before {
  content: '';
  position: absolute;
  left: -33px; top: 4px;
  width: 10px; height: 10px;
  border-radius: 50%;
  background: var(--gold);
  box-shadow: 0 0 0 3px var(--navy);
}
.timeline-date {
  font-family: var(--mono);
  color: var(--cyan);
  font-size: 0.82rem;
  margin-bottom: 4px;
}
.timeline-title {
  font-family: var(--serif);
  font-weight: 600;
  color: var(--chalk);
  font-size: 1.05rem;
  margin-bottom: 4px;
}
.timeline-desc { color: var(--chalk-dim); font-size: 0.92rem; margin: 0; }

/* ---------- numbered step list (proofs, derivations) ---------- */
.step-list { display: flex; flex-direction: column; gap: 16px; }
.step-list .proof-step { display: flex; gap: 14px; align-items: flex-start; }
.step-list .proof-step-num {
  flex-shrink: 0;
  width: 26px; height: 26px;
  border-radius: 50%;
  border: var(--border);
  color: var(--gold);
  font-family: var(--mono);
  font-size: 0.8rem;
  display: flex; align-items: center; justify-content: center;
}
.step-list .proof-step p { margin: 0; font-size: 0.92rem; color: var(--chalk-dim); }
.step-list .proof-step p .math { color: var(--cyan); font-family: var(--mono); }