/* ============================================================
   Econ 101A — style.css  v2  (WebGL + D3 edition)
   ============================================================ */

/* ── Design tokens ───────────────────────────────────────── */
:root {
  --bblue:    #003262;
  --bgold:    #FDB515;
  --bgoldd:   #C4820A;
  --t1:       #1e64b4;
  --t1bg:     #eef4fc;
  --t2:       #b47800;
  --t2bg:     #fdf6e3;
  --t3:       #007840;
  --t3bg:     #e8f5ee;
  --alert:    #b41e1e;
  --alertbg:  #fdf0f0;
  --keybg:    #fffbea;
  --formbg:   #eef3fb;
  --sidebar:  260px;
  --r:        8px;
  --shadow:   0 2px 10px rgba(0,0,0,.10);
  --hero-h:   100vh;
  --trans:    .18s ease;
}

/* dark mode */
body.dark {
  --bg: #0d1117; --surface: #161b22; --text: #e6edf3;
  --border: #30363d; --muted: #8b949e;
}

*,*::before,*::after { box-sizing: border-box; margin:0; padding:0; }
html { scroll-behavior: smooth; }

body {
  font-family: Georgia, 'Times New Roman', serif;
  font-size: 15px;
  line-height: 1.75;
  color: #1a1a1a;
  background: #f2f1ee;
  transition: background var(--trans), color var(--trans);
}
body.dark { background: #0d1117; color: #e6edf3; }

/* ── Hero ───────────────────────────────────────────────── */
.hero {
  position: relative;
  height: var(--hero-h);
  min-height: 560px;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  background: #000e1e;
}

.hero-canvas {
  position: absolute;
  inset: 0;
  z-index: 0;
}
.hero-canvas canvas { width: 100% !important; height: 100% !important; }

.hero-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(
    135deg,
    rgba(0,20,50,.82) 0%,
    rgba(0,10,30,.55) 60%,
    rgba(0,0,0,.30) 100%
  );
  z-index: 1;
}

.hero-content {
  position: relative;
  z-index: 2;
  text-align: center;
  color: #fff;
  padding: 0 24px;
  max-width: 780px;
}

.hero-badge {
  display: inline-block;
  background: rgba(253,181,21,.18);
  border: 1px solid rgba(253,181,21,.55);
  color: var(--bgold);
  font-family: sans-serif;
  font-size: .78rem;
  letter-spacing: .12em;
  text-transform: uppercase;
  padding: 5px 16px;
  border-radius: 20px;
  margin-bottom: 20px;
}

.hero-title {
  font-size: clamp(2.2rem, 6vw, 4.2rem);
  font-weight: 700;
  line-height: 1.1;
  color: #fff;
  margin-bottom: 10px;
  text-shadow: 0 2px 20px rgba(0,0,0,.6);
}

.hero-sub {
  font-size: 1.05rem;
  color: rgba(255,255,255,.7);
  font-family: sans-serif;
  margin-bottom: 28px;
  letter-spacing: .04em;
}

.hero-chips {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 8px;
  margin-bottom: 28px;
}

.chip {
  display: inline-block;
  padding: 6px 14px;
  border: 1px solid rgba(255,255,255,.3);
  border-radius: 20px;
  color: #fff;
  text-decoration: none;
  font-family: sans-serif;
  font-size: .8rem;
  transition: background var(--trans), border-color var(--trans);
  backdrop-filter: blur(6px);
  background: rgba(255,255,255,.08);
}
.chip:hover { background: rgba(255,255,255,.2); border-color: rgba(255,255,255,.6); }
.chip-gold { background: rgba(253,181,21,.25); border-color: var(--bgold); color: var(--bgold); font-weight: 600; }
.chip-gold:hover { background: rgba(253,181,21,.4); }

.hero-controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 12px 20px;
  background: rgba(0,0,0,.45);
  backdrop-filter: blur(8px);
  border: 1px solid rgba(255,255,255,.12);
  border-radius: 12px;
  padding: 12px 20px;
  font-family: sans-serif;
  font-size: .82rem;
  color: rgba(255,255,255,.8);
}
.ctrl-label { font-weight: 600; color: var(--bgold); width: 100%; text-align: center; margin-bottom: 2px; }
.hero-controls label { display: flex; align-items: center; gap: 7px; }
.hero-controls input[type=range] { width: 90px; accent-color: var(--bgold); }
.hero-controls span { min-width: 28px; text-align: right; color: var(--bgold); font-weight: 600; }

.hero-scroll {
  position: absolute;
  bottom: 28px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 2;
  color: rgba(255,255,255,.5);
  font-size: 1.5rem;
  text-decoration: none;
  animation: bounce 2s infinite;
}
@keyframes bounce {
  0%,100% { transform: translateX(-50%) translateY(0); }
  50%      { transform: translateX(-50%) translateY(8px); }
}

/* ── Layout ──────────────────────────────────────────────── */
.layout { display: flex; min-height: 100vh; }

/* ── Sidebar ─────────────────────────────────────────────── */
.sidebar {
  width: var(--sidebar);
  background: var(--bblue);
  color: #cce;
  position: fixed;
  top: 0; left: 0; bottom: 0;
  overflow-y: auto;
  z-index: 100;
  display: flex;
  flex-direction: column;
  box-shadow: 3px 0 16px rgba(0,0,0,.18);
}

.sidebar-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 20px 16px 14px;
  border-bottom: 2px solid var(--bgold);
}
.logo-icon {
  font-size: 2rem;
  color: var(--bgold);
  font-family: serif;
  line-height: 1;
  flex-shrink: 0;
}
.logo-title { font-size: 1rem; color: #fff; font-weight: 700; }
.logo-sub   { font-size: .72rem; color: var(--bgold); font-family: sans-serif; }

.sidebar nav { flex: 1; padding: 8px 0 20px; }

.nav-group { margin-top: 2px; }
.nav-group-label {
  font-size: .65rem;
  text-transform: uppercase;
  letter-spacing: .12em;
  color: #7788bb;
  padding: 10px 18px 3px;
  font-family: sans-serif;
}
.sidebar a {
  display: block;
  padding: 6px 18px 6px 22px;
  color: #bbd;
  text-decoration: none;
  font-size: .8rem;
  font-family: sans-serif;
  transition: background var(--trans), color var(--trans), border-left-color var(--trans);
  border-left: 3px solid transparent;
}
.sidebar a:hover { background: rgba(253,181,21,.1); color: #fff; }
.sidebar a.active {
  background: rgba(253,181,21,.16);
  color: var(--bgold);
  border-left-color: var(--bgold);
  font-weight: 600;
}

.sidebar-footer { padding: 12px 16px 20px; }
.dark-toggle {
  width: 100%;
  padding: 7px;
  background: rgba(255,255,255,.07);
  border: 1px solid rgba(255,255,255,.15);
  border-radius: 6px;
  color: #aac;
  font-family: sans-serif;
  font-size: .8rem;
  cursor: pointer;
  transition: background var(--trans);
}
.dark-toggle:hover { background: rgba(255,255,255,.14); color: #fff; }

/* ── Main ────────────────────────────────────────────────── */
.main {
  margin-left: var(--sidebar);
  flex: 1;
  padding: 0 36px 100px;
  max-width: calc(100% - var(--sidebar));
}

/* ── Section ─────────────────────────────────────────────── */
.section {
  margin-top: 56px;
  scroll-margin-top: 24px;
  /* Reveal animation */
  opacity: 0;
  transform: translateY(28px);
  transition: opacity .5s ease, transform .5s ease;
}
.section.visible { opacity: 1; transform: translateY(0); }

.section-title {
  font-size: 1.5rem;
  color: var(--bblue);
  border-bottom: 3px solid var(--bgold);
  padding-bottom: 7px;
  margin-bottom: 18px;
}
body.dark .section-title { color: #7ab0ff; border-bottom-color: var(--bgold); }
.section-title span {
  font-size: .82rem;
  color: #999;
  font-family: sans-serif;
  font-weight: 400;
  margin-left: 10px;
}

/* ── Two-column layout ───────────────────────────────────── */
.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  align-items: start;
}
@media (max-width: 900px) { .two-col { grid-template-columns: 1fr; } }

/* ── Viz panel ───────────────────────────────────────────── */
.viz-panel {
  background: #fff;
  border: 1px solid #e0e0e0;
  border-radius: var(--r);
  padding: 14px 12px 8px;
  box-shadow: var(--shadow);
}
body.dark .viz-panel { background: #161b22; border-color: #30363d; }
.viz-title {
  font-family: sans-serif;
  font-size: .82rem;
  font-weight: 700;
  color: var(--bblue);
  margin-bottom: 6px;
  text-transform: uppercase;
  letter-spacing: .06em;
}
body.dark .viz-title { color: var(--bgold); }
.viz-legend {
  font-family: sans-serif;
  font-size: .72rem;
  color: #777;
  margin-bottom: 8px;
  display: flex;
  flex-wrap: wrap;
  gap: 6px 12px;
}

/* ── Side-note box ───────────────────────────────────────── */
.side-note-box {
  background: #f8f6f0;
  border: 1px solid #e8e0cc;
  border-radius: var(--r);
  padding: 16px 18px;
}
body.dark .side-note-box { background: #1c2128; border-color: #30363d; }
.side-note-title {
  font-family: sans-serif;
  font-size: .78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--bblue);
  margin-bottom: 10px;
}

.mini-table { width: 100%; border-collapse: collapse; font-family: sans-serif; font-size: .82rem; }
.mini-table th { background: var(--bblue); color: #fff; padding: 5px 8px; text-align: left; }
.mini-table td { padding: 5px 8px; border-bottom: 1px solid #e8e0cc; }
.mini-table tr:hover td { background: #f0ece0; }

/* ── Tier tabs ───────────────────────────────────────────── */
.tier-tabs {
  display: flex;
  gap: 3px;
  border-bottom: 2px solid #ddd;
  margin-bottom: 0;
}
.tier-tab {
  padding: 6px 16px;
  border: none;
  background: #e4e4e4;
  cursor: pointer;
  font-size: .8rem;
  font-family: sans-serif;
  border-radius: 6px 6px 0 0;
  color: #666;
  transition: background var(--trans), color var(--trans);
}
.tier-tab[data-tier="1"].active { background: var(--t1); color: #fff; }
.tier-tab[data-tier="2"].active { background: var(--t2); color: #fff; }
.tier-tab[data-tier="3"].active { background: var(--t3); color: #fff; }
.tier-tab:not(.active):hover { background: #ccc; }

.tier-panel {
  display: none;
  padding: 16px 18px;
  border: 1px solid #ddd;
  border-top: none;
  border-radius: 0 0 var(--r) var(--r);
  background: #fff;
}
.tier-panel.active { display: block; }
.tier-panel[data-tier="1"] { border-top: 3px solid var(--t1); }
.tier-panel[data-tier="2"] { border-top: 3px solid var(--t2); }
.tier-panel[data-tier="3"] { border-top: 3px solid var(--t3); }
body.dark .tier-panel { background: #161b22; border-color: #30363d; }

.tier-badge {
  display: inline-block;
  font-size: .7rem;
  font-family: sans-serif;
  font-weight: 700;
  padding: 2px 9px;
  border-radius: 3px;
  margin-bottom: 10px;
  letter-spacing: .04em;
}
.tier-badge.t1 { background: var(--t1bg); color: var(--t1); border: 1px solid var(--t1); }
.tier-badge.t2 { background: var(--t2bg); color: var(--t2); border: 1px solid var(--t2); }
.tier-badge.t3 { background: var(--t3bg); color: var(--t3); border: 1px solid var(--t3); }

/* ── Boxes ───────────────────────────────────────────────── */
.box { border-radius: 6px; padding: 12px 16px; margin: 12px 0; }
.box-key   { background: var(--keybg);  border-left: 4px solid var(--bgoldd); }
.box-alert { background: var(--alertbg); border-left: 4px solid var(--alert); }
.box-formula { background: var(--formbg); border-left: 4px solid var(--bblue); }
.box-title {
  font-weight: 700; font-family: sans-serif; font-size: .75rem;
  text-transform: uppercase; letter-spacing: .05em; margin-bottom: 6px;
}
.box-key .box-title   { color: var(--bgoldd); }
.box-alert .box-title { color: var(--alert); }
.box-formula .box-title { color: var(--bblue); }

/* ── Calculator cards ────────────────────────────────────── */
.calc-card {
  background: #fff;
  border: 1px solid #dde;
  border-radius: var(--r);
  padding: 16px 18px;
  margin: 16px 0;
  box-shadow: var(--shadow);
}
body.dark .calc-card { background: #161b22; border-color: #30363d; }

.calc-card-title {
  font-family: sans-serif;
  font-size: .88rem;
  font-weight: 700;
  color: var(--bblue);
  margin-bottom: 12px;
  display: flex; align-items: center; gap: 6px;
}
body.dark .calc-card-title { color: var(--bgold); }

/* Real-time sliders */
.slider-row {
  display: flex; align-items: center; gap: 10px;
  margin: 7px 0;
  font-family: sans-serif; font-size: .82rem; color: #555;
}
body.dark .slider-row { color: #aaa; }
.slider-row label { min-width: 120px; }
.slider-row input[type=range] { flex: 1; accent-color: var(--bblue); height: 4px; }
.slider-row span { min-width: 36px; text-align: right; font-weight: 700; color: var(--bblue); font-size: .85rem; }
body.dark .slider-row span { color: var(--bgold); }

.calc-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 10px;
  margin-bottom: 12px;
}
.calc-field label {
  display: block; font-size: .75rem; font-family: sans-serif; color: #666; margin-bottom: 3px;
}
.calc-field input {
  width: 100%; padding: 6px 10px; border: 1px solid #ccc;
  border-radius: 5px; font-size: .88rem; font-family: sans-serif;
}
.calc-field input:focus { outline: 2px solid var(--bgold); border-color: var(--bgold); }

.calc-btn {
  background: var(--bblue); color: #fff; border: none;
  padding: 8px 22px; border-radius: 5px;
  font-size: .85rem; font-family: sans-serif; cursor: pointer;
  transition: background var(--trans);
}
.calc-btn:hover { background: #004a8c; }

.calc-result, .calc-output {
  margin-top: 12px; padding: 12px 14px;
  background: var(--t2bg); border: 1px solid #dbc860;
  border-radius: 5px; font-family: sans-serif; font-size: .84rem;
  display: none;
}
.calc-result.show, .calc-output.show { display: block; }
.calc-result strong, .calc-output strong { color: var(--bblue); }

/* ── Tables ──────────────────────────────────────────────── */
table.styled {
  width: 100%; border-collapse: collapse;
  font-size: .82rem; font-family: sans-serif; margin: 8px 0;
}
table.styled th { background: var(--bblue); color: #fff; padding: 7px 10px; text-align: left; }
table.styled td { padding: 6px 10px; border-bottom: 1px solid #e4e4e4; }
table.styled tr:nth-child(even) td { background: #f8f8f6; }
table.styled tr:hover td { background: #f0f4ff; }

/* ── Step list ───────────────────────────────────────────── */
.step {
  display: flex; gap: 10px; margin: 8px 0;
  padding: 9px 12px; background: #f6f4f0;
  border-radius: 5px; border-left: 3px solid var(--bgold);
  font-family: sans-serif; font-size: .85rem;
}
.step-num { font-weight: 700; color: var(--bblue); min-width: 22px; }
body.dark .step { background: #1c2128; }

/* ── Formula bank ────────────────────────────────────────── */
.search-input {
  width: 100%; padding: 10px 16px;
  border: 2px solid var(--bblue); border-radius: var(--r);
  font-size: .95rem; font-family: sans-serif;
  margin-bottom: 12px; background: #fff;
}
.search-input:focus { outline: none; border-color: var(--bgoldd); }
body.dark .search-input { background: #161b22; color: #e6edf3; border-color: #7ab0ff; }

.formula-row {
  display: flex; gap: 12px; padding: 9px 12px;
  border-bottom: 1px solid #eee; align-items: flex-start;
  font-family: sans-serif; font-size: .82rem; transition: background var(--trans);
}
.formula-row:hover { background: #f6f4f0; }
body.dark .formula-row:hover { background: #1c2128; }
.formula-row .f-name { width: 200px; flex-shrink: 0; font-weight: 600; color: var(--bblue); }
body.dark .formula-row .f-name { color: #7ab0ff; }
.formula-row .f-expr { flex: 1; }
.formula-row .f-tag {
  font-size: .68rem; background: var(--bblue); color: #fff;
  padding: 2px 7px; border-radius: 3px; white-space: nowrap; height: fit-content;
}

/* ── Atlas ───────────────────────────────────────────────── */
.atlas-intro { font-family: sans-serif; font-size: .88rem; color: #666; margin-bottom: 18px; }
.atlas-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(290px, 1fr));
  gap: 14px;
}
.atlas-card {
  background: #fff; border: 1px solid #ddd;
  border-radius: var(--r); overflow: hidden;
  cursor: pointer; box-shadow: var(--shadow);
  transition: box-shadow var(--trans), transform var(--trans);
}
.atlas-card:hover { box-shadow: 0 6px 20px rgba(0,50,98,.16); transform: translateY(-3px); }
body.dark .atlas-card { background: #161b22; border-color: #30363d; }
.atlas-trigger {
  background: var(--bblue); color: var(--bgold);
  padding: 12px 15px; font-size: .82rem;
  font-family: sans-serif; font-weight: 600; line-height: 1.4;
}
.atlas-trigger .alabel {
  font-size: .65rem; color: #88aacc; margin-bottom: 3px;
  text-transform: uppercase; letter-spacing: .07em;
}
.atlas-tool {
  padding: 12px 15px; font-size: .8rem;
  font-family: sans-serif; color: #444;
  border-top: 2px solid var(--bgold);
  background: var(--keybg);
  display: none;
  line-height: 1.6;
}
body.dark .atlas-tool { background: #1c2128; color: #ccc; }
.atlas-tool.show { display: block; }
.atlas-hint {
  font-size: .68rem; color: #bbb; text-align: right;
  padding: 3px 12px 7px; font-family: sans-serif;
}

/* ── Typography ──────────────────────────────────────────── */
p { margin: 7px 0; }
ul, ol { margin: 7px 0 7px 22px; }
li { margin: 3px 0; }
strong { color: var(--bblue); }
body.dark strong { color: #7ab0ff; }
em { color: #555; }
body.dark em { color: #8b949e; }

/* ── Download cards ──────────────────────────────────────── */
.download-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
}
.download-card {
  display: flex; gap: 14px; align-items: flex-start;
  padding: 18px 18px; border-radius: var(--r);
  background: #fff; border: 1.5px solid #e2e6ee;
  text-decoration: none; color: inherit;
  transition: transform .18s, box-shadow .18s, border-color .18s;
}
.download-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 20px rgba(0,50,98,.12);
  border-color: var(--bblue);
}
.dl-icon { font-size: 1.8rem; line-height: 1; flex-shrink: 0; margin-top: 2px; }
.dl-title { font-weight: 700; font-size: .95rem; color: var(--bblue); margin-bottom: 4px; }
.dl-desc { font-size: .82rem; color: #555; line-height: 1.45; margin-bottom: 6px; }
.dl-meta { font-size: .75rem; color: #999; font-family: monospace; }
body.dark .download-card { background: #161b22; border-color: #30363d; }
body.dark .download-card:hover { border-color: #7ab0ff; }
body.dark .dl-desc { color: #aaa; }

/* ── Mobile ──────────────────────────────────────────────── */
@media (max-width: 768px) {
  .sidebar { transform: translateX(-100%); transition: transform .28s ease; }
  .sidebar.open { transform: translateX(0); }
  .main { margin-left: 0; padding: 0 14px 60px; max-width: 100%; }
  .hero-title { font-size: 2.2rem; }
  .menu-btn { display: flex; }
}
@media (min-width: 769px) { .menu-btn { display: none !important; } }

.menu-btn {
  position: fixed; bottom: 22px; right: 22px;
  background: var(--bblue); color: #fff; border: none;
  border-radius: 50%; width: 52px; height: 52px;
  font-size: 1.3rem; align-items: center; justify-content: center;
  z-index: 200; cursor: pointer;
  box-shadow: 0 4px 14px rgba(0,0,0,.3);
  transition: background var(--trans);
}
.menu-btn:hover { background: #004a8c; }