:root {
  --ink: #1c1915;
  --muted: #5c564c;
  --faint: #8a8378;
  --paper: #f6f3ec;
  --panel: #efeae1;
  --line: #d9d2c5;
  --accent: #1e4d3a;
  --accent-soft: #e5efe9;
  --warn: #8a3d2f;
  --warn-soft: #f8ebe6;
  --ok: #1e4d3a;
  --shadow: none;
  color-scheme: light;
  font-family: "Segoe UI", "Source Sans 3", sans-serif;
}

* { box-sizing: border-box; }

html, body { margin: 0; background: var(--paper); color: var(--ink); }

.app {
  display: grid;
  grid-template-columns: 300px minmax(0, 1fr);
  min-height: 100vh;
}

aside {
  border-right: 1px solid var(--line);
  background: var(--panel);
  padding: 28px 18px 40px;
  position: sticky;
  top: 0;
  height: 100vh;
  overflow: auto;
}

.eyebrow {
  margin: 0;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-size: 11px;
  color: var(--accent);
  font-weight: 650;
}

.brand h1 {
  font-family: Palatino, "Palatino Linotype", Georgia, serif;
  font-size: 32px;
  font-weight: 600;
  margin: 6px 0 8px;
}

.brand-note {
  margin: 0 0 18px;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.45;
}

.stage-label {
  margin: 16px 8px 6px;
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--faint);
}

.ladder-btn {
  display: block;
  width: 100%;
  text-align: left;
  border: 0;
  background: transparent;
  color: var(--ink);
  padding: 7px 10px;
  border-left: 2px solid transparent;
  cursor: pointer;
  font: inherit;
  font-size: 14px;
  line-height: 1.35;
}

.ladder-btn:hover { background: rgba(255, 255, 255, 0.45); }

.ladder-btn[aria-current="true"] {
  border-left-color: var(--accent);
  background: #fff;
  font-weight: 650;
}

main {
  padding: 36px 48px 64px;
  max-width: 920px;
}

.meter {
  display: flex;
  gap: 6px;
  margin: 0 0 14px;
}

.meter span {
  height: 6px;
  width: 56px;
  background: var(--line);
}

.meter span.on { background: var(--accent); }

.kicker {
  margin: 0;
  color: var(--accent);
  font-size: 13px;
  font-weight: 650;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

h2 {
  font-family: Palatino, "Palatino Linotype", Georgia, serif;
  font-size: 34px;
  line-height: 1.15;
  font-weight: 600;
  margin: 8px 0 12px;
}

.idea {
  font-family: Palatino, "Palatino Linotype", Georgia, serif;
  font-size: 22px;
  line-height: 1.35;
  margin: 0 0 18px;
}

.rests {
  color: var(--muted);
  font-size: 14px;
  margin: 0 0 18px;
}

.prose p {
  font-family: Palatino, "Palatino Linotype", Georgia, serif;
  font-size: 18px;
  line-height: 1.55;
  margin: 0 0 14px;
}

figure.diagram {
  margin: 8px 0 22px;
  border: 1px solid var(--line);
  background: #fbfaf7;
  padding: 16px 16px 10px;
}

figure.diagram svg, figure.diagram .fig-html { width: 100%; height: auto; display: block; }

figcaption {
  color: var(--muted);
  font-size: 13px;
  line-height: 1.4;
  margin-top: 8px;
}

.precision {
  border-left: 3px solid var(--accent);
  background: var(--accent-soft);
  padding: 12px 14px;
  margin: 6px 0 22px;
}

.precision strong {
  display: block;
  font-size: 12px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 4px;
}

.precision p { margin: 0; font-size: 15px; line-height: 1.45; }

.check {
  margin-top: 8px;
  padding-top: 8px;
}

.check h3 {
  font-family: Palatino, "Palatino Linotype", Georgia, serif;
  font-size: 20px;
  margin: 18px 0 8px;
}

.prompt { margin: 0 0 10px; font-size: 16px; line-height: 1.45; }

.choice {
  display: block;
  width: 100%;
  text-align: left;
  margin: 0 0 8px;
  padding: 10px 12px;
  border: 1px solid var(--line);
  background: #fff;
  font: inherit;
  font-size: 15px;
  cursor: pointer;
  color: var(--ink);
}

.choice:hover { border-color: var(--accent); }

.choice.right { border-color: var(--ok); background: var(--accent-soft); }
.choice.wrong { border-color: var(--warn); background: var(--warn-soft); }
.choice:disabled { cursor: default; }

.why {
  margin: 4px 0 16px;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.45;
}

.pager {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin-top: 28px;
}

.pager button {
  border: 1px solid var(--ink);
  background: var(--ink);
  color: #fff;
  font: inherit;
  padding: 10px 14px;
  cursor: pointer;
}

.pager button:disabled {
  background: transparent;
  color: var(--faint);
  border-color: var(--line);
  cursor: default;
}

#prev { background: transparent; color: var(--ink); }

.grid-fig {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
}

.grid-fig th, .grid-fig td {
  border: 1px solid var(--line);
  padding: 8px;
  text-align: center;
}

.grid-fig th { background: var(--panel); font-weight: 650; }

.cards { display: flex; flex-wrap: wrap; gap: 10px; }
.card {
  border: 1px solid var(--line);
  background: #fff;
  padding: 10px 12px;
  min-width: 120px;
}
.card b { display: block; font-size: 16px; }
.card span { color: var(--muted); font-size: 13px; }

.gen-row { display: flex; gap: 16px; align-items: center; margin: 8px 0; }
.gen-label { width: 72px; color: var(--muted); font-size: 13px; }
.arrow { color: var(--faint); padding: 0 4px; }

.words { display: flex; flex-wrap: wrap; gap: 6px; margin: 0 0 16px; }
.words span {
  border: 1px solid var(--line);
  background: #fff;
  padding: 2px 8px;
  font-size: 12px;
  letter-spacing: 0.02em;
}

.work {
  border-left: 3px solid var(--warn);
  background: var(--warn-soft);
  padding: 12px 14px;
  margin: 6px 0 22px;
}
.work .prompt { margin: 0 0 8px; }
.work summary {
  cursor: pointer;
  font-size: 14px;
  font-weight: 650;
}
.work summary:focus-visible { outline: 2px solid var(--warn); outline-offset: 2px; }
.work ol { margin: 8px 0 0; padding-left: 18px; }
.work li { margin: 0 0 6px; font-size: 15px; line-height: 1.45; }

.precision summary {
  cursor: pointer;
  font-size: 12px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  font-weight: 650;
  color: var(--accent);
}
.precision summary:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.precision p { margin: 8px 0 0; }

.entrance {
  margin-top: 8px;
  padding-top: 4px;
  border-top: 1px solid var(--line);
}
.entrance h3 {
  font-family: Palatino, "Palatino Linotype", Georgia, serif;
  font-size: 20px;
  margin: 16px 0 8px;
}
.entrance > p {
  font-size: 15px;
  line-height: 1.5;
  margin: 0 0 12px;
}
.drill-item { margin: 0 0 16px; }

.widget { margin-top: 12px; }
.widget label { display: block; font-size: 14px; margin: 0 0 8px; }
.widget select, .widget input[type="range"] { font: inherit; }
.widget select { padding: 6px 8px; background: #fff; border: 1px solid var(--line); color: var(--ink); }
.widget .result { margin: 8px 0 0; font-size: 15px; }

.stack-bar { display: flex; height: 22px; width: 100%; border: 1px solid var(--line); margin-top: 8px; }
.stack-bar div { height: 100%; }
.seg-dom { background: var(--accent); }
.seg-het { background: #7d9a86; }
.seg-rec { background: var(--warn); }
.legend { display: flex; gap: 14px; margin-top: 6px; font-size: 12px; color: var(--muted); }
.legend i { display: inline-block; width: 10px; height: 10px; margin-right: 4px; vertical-align: -1px; }

.hw-story { max-width: 40rem; }
.hw-step { margin: 18px 0 8px; font-weight: 650; color: var(--accent); }
.hw-copies {
  display: grid;
  grid-template-columns: repeat(10, minmax(0, 36px));
  gap: 8px;
  margin: 4px 0 8px;
  max-width: 100%;
}
.hw-chip {
  width: 100%;
  aspect-ratio: 1;
  border-radius: 50%;
  display: grid;
  place-items: center;
  color: #fff;
  font-weight: 650;
}
.hw-chip.bigA { background: var(--accent); }
.hw-chip.smalla { background: var(--warn); }
.hw-meet { width: 100%; border-collapse: collapse; margin: 8px 0 12px; }
.hw-meet th, .hw-meet td {
  border: 1px solid var(--line);
  padding: 10px 8px;
  text-align: center;
  vertical-align: middle;
}
.hw-meet th { background: var(--panel); font-weight: 650; font-size: 14px; }
.hw-meet td b { display: block; font-size: 20px; }
.hw-meet td span { display: block; margin-top: 4px; color: var(--muted); font-size: 13px; }
.hw-meet td.het { background: var(--accent-soft); }
.hw-meet td.dom { background: #f7faf8; }
.hw-meet td.rec { background: var(--warn-soft); }
.hw-formula { margin: 6px 0; font-size: 18px; color: var(--accent); }

.codon-wrap { overflow-x: auto; }
.codon-table { font-size: 12px; min-width: 520px; }
.codon-table td.stop { color: var(--warn); font-weight: 650; }

.source {
  margin: 22px 0 0;
  color: var(--faint);
  font-size: 12px;
  line-height: 1.4;
}

.choice:focus-visible, .ladder-btn:focus-visible, .pager button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

@media (prefers-reduced-motion: no-preference) {
  .rise {
    animation: rise 0.7s ease both;
  }
  .d1 { animation-delay: 0.25s; }
  .d2 { animation-delay: 0.55s; }
  .d3 { animation-delay: 0.9s; }
  .d4 { animation-delay: 1.2s; }
  .d5 { animation-delay: 1.55s; }
  .d6 { animation-delay: 1.9s; }

  .draw {
    stroke-dasharray: 120;
    stroke-dashoffset: 120;
    animation: draw 0.9s ease forwards;
  }
  .draw.long {
    stroke-dasharray: 700;
    stroke-dashoffset: 700;
    animation-duration: 1.6s;
  }
  .draw.d2 { animation-delay: 0.45s; }
  .draw.d3 { animation-delay: 0.9s; }

  .bond {
    stroke-dasharray: 90;
    stroke-dashoffset: 90;
    animation: draw 0.45s ease forwards;
  }

  .pop {
    transform-box: fill-box;
    transform-origin: center;
    animation: pop 0.45s ease both;
  }

  .slide-pair {
    animation: slide-pair 3.2s ease-in-out infinite;
  }

  .lift {
    transform-box: fill-box;
    animation: lift 2.8s ease-in-out infinite;
  }

  .pulse-letter {
    animation: pulse-letter 1.6s ease-in-out infinite;
  }

  .flow {
    animation: flow 2.4s ease-in-out infinite;
  }

  @keyframes rise {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: none; }
  }
  @keyframes draw {
    to { stroke-dashoffset: 0; }
  }
  @keyframes pop {
    from { opacity: 0; transform: scale(0.6); }
    to { opacity: 1; transform: none; }
  }
  @keyframes slide-pair {
    0%, 35% { transform: translate(0, 0); }
    55%, 100% { transform: translate(28px, 0); }
  }
  @keyframes lift {
    0%, 30% { transform: translate(0, 0); }
    55%, 80% { transform: translate(0, -28px); }
    100% { transform: translate(0, 0); }
  }
  @keyframes pulse-letter {
    0%, 100% { fill: #1c1915; color: #1c1915; }
    40% { fill: #8a3d2f; color: #8a3d2f; }
  }
  @keyframes flow {
    0%, 100% { transform: translateX(0); opacity: 0.35; }
    50% { transform: translateX(10px); opacity: 1; }
  }
}

@media (prefers-reduced-motion: reduce) {
  .rise, .draw, .bond, .pop, .slide-pair, .lift, .pulse-letter, .flow {
    animation: none;
  }
}

body.home {
  max-width: 960px;
  margin: 0 auto;
  padding: 36px 24px 64px;
}
.home-head h1 {
  font-family: Palatino, "Palatino Linotype", Georgia, serif;
  font-size: 48px;
  font-weight: 600;
  margin: 8px 0 12px;
}
.lede {
  font-family: Palatino, "Palatino Linotype", Georgia, serif;
  font-size: 20px;
  line-height: 1.45;
  max-width: 42rem;
  margin: 0 0 16px;
}
.study-link {
  display: inline-block;
  background: var(--ink);
  color: #fff;
  text-decoration: none;
  padding: 10px 14px;
}
.study-link:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }
.player { margin: 28px 0 8px; }
.player video {
  width: 100%;
  height: auto;
  background: #1c1915;
  display: block;
}
.player figcaption {
  margin-top: 8px;
}
.chapters {
  display: flex;
  flex-direction: column;
  gap: 8px;
  max-width: 40rem;
}
.chapter-row { display: flex; gap: 8px; align-items: center; }
.chapter-row button { flex: 1; }
.core a { color: var(--accent); }
.chapters button {
  text-align: left;
  font: inherit;
  font-size: 15px;
  background: #fff;
  color: var(--ink);
  border: 1px solid var(--line);
  padding: 10px 12px;
  cursor: pointer;
}
.chapters button:hover { border-color: var(--accent); }
.chapters button:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.brand-note a { color: var(--accent); }

.onion-help {
  color: var(--muted);
  font-size: 14px;
  margin: 0 0 12px;
}
.ring {
  position: relative;
  border-left: 3px solid var(--line);
  padding: 8px 12px 8px 14px;
  margin: 0 0 8px;
  cursor: help;
}
.ring:hover, .ring:focus, .ring.open { border-left-color: var(--accent); background: #fff; }
.ring-line { margin: 0; font-family: Palatino, "Palatino Linotype", Georgia, serif; font-size: 20px; line-height: 1.35; }
.ring-n {
  display: inline-block;
  width: 1.4em;
  color: var(--accent);
  font-family: "Segoe UI", sans-serif;
  font-size: 14px;
  font-weight: 650;
}
.support {
  display: none;
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 15px;
  line-height: 1.45;
  max-width: 42rem;
}
.ring:hover .support, .ring:focus .support, .ring.open .support { display: block; }
.core {
  font-family: Palatino, "Palatino Linotype", Georgia, serif;
  font-size: 22px;
  line-height: 1.35;
  margin: 16px 0;
  padding: 12px 14px;
  background: var(--accent-soft);
  border-left: 3px solid var(--accent);
}
.jumps { display: flex; flex-wrap: wrap; gap: 8px; margin: 0 0 18px; }
.jumps a, .home-jump {
  color: var(--accent);
  text-decoration: none;
  border: 1px solid var(--line);
  background: #fff;
  padding: 8px 10px;
  font-size: 14px;
}
.jumps a:hover, .home-jump:hover { border-color: var(--accent); }
.share {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin: 12px 0;
  font-size: 14px;
}
.share span { color: var(--muted); margin-right: 2px; }
.share a {
  color: var(--accent);
  text-decoration: none;
  border: 1px solid var(--line);
  background: #fff;
  padding: 6px 10px;
}
.share a:hover { border-color: var(--accent); }
.share a:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.home-onion { margin: 8px 0 28px; }
.home-ring {
  display: grid;
  grid-template-columns: 220px minmax(0, 1fr);
  gap: 16px;
  align-items: center;
  margin: 0 0 14px;
  position: relative;
}
.home-ring figure.diagram { margin: 0; padding: 8px; }
.home-ring .ring { margin: 0; }
@media (max-width: 700px) {
  .home-ring { grid-template-columns: 1fr; }
}

@media (max-width: 700px) {
  .app { display: flex; flex-direction: column; }
  .app main { order: -1; padding: 24px 18px 48px; }
  aside {
    position: relative;
    height: auto;
    max-height: 38vh;
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }
  h2 { font-size: 28px; }
}