:root {
  --paper: #efe7d2;
  --paper-warm: #ece4cf;
  --paper-dark: #ddd2b6;
  --bone: #f7f1de;
  --ink: #15140f;
  --ink-soft: #2a2620;
  --ink-mute: #5a5448;
  --ink-faint: #8b8676;
  --coral: #ed6f5c;
  --mustard: #e9b94a;
  --slide-w: 1280px;
  --slide-h: 720px;

  --font-sans: "Inter", -apple-system, "PingFang SC", "Hiragino Sans GB", sans-serif;
  --font-display: "Inter", "Inter Tight", -apple-system, sans-serif;
  --font-serif: "Playfair Display", "Source Han Serif SC", Georgia, serif;
  --font-mono: "JetBrains Mono", ui-monospace, "SF Mono", Menlo, monospace;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
html, body { width: 100%; height: 100%; overflow: hidden; background: #1a1814; }
body {
  font-family: var(--font-sans);
  color: var(--ink);
  display: flex; align-items: center; justify-content: center;
}
.deck { position: relative; width: var(--slide-w); height: var(--slide-h); overflow: hidden; }
.deck-track { display: flex; width: 100%; height: 100%; transition: transform 0.25s cubic-bezier(0.23,1,0.32,1); }
.deck-track.is-instant { transition-duration: 0s; }
.slide {
  width: var(--slide-w); height: var(--slide-h); flex-shrink: 0;
  background: var(--paper); position: relative; overflow: hidden;
  padding: 56px 80px 48px;
}
.slide.dark { background: var(--ink); color: var(--paper); }
.slide.dark .em { color: var(--coral); }
.slide.dark .ink-faint { color: var(--paper-dark); opacity: 0.7; }

/* paper noise */
.slide::before {
  content: ""; position: absolute; inset: 0; pointer-events: none;
  background:
    radial-gradient(ellipse at 20% 30%, rgba(106,92,56,0.05), transparent 50%),
    radial-gradient(ellipse at 80% 80%, rgba(106,92,56,0.03), transparent 60%);
  mix-blend-mode: multiply;
}
.slide::after {
  content: ""; position: absolute; inset: 0; pointer-events: none;
  opacity: 0.05;
  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='200' height='200'><filter id='n'><feTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2'/></filter><rect width='100%25' height='100%25' filter='url(%23n)'/></svg>");
  mix-blend-mode: multiply;
}
.slide.dark::after { mix-blend-mode: screen; opacity: 0.08; }

/* per-slide chrome */
.chrome {
  position: absolute; left: 80px; right: 80px; bottom: 28px;
  display: flex; justify-content: space-between; align-items: baseline;
  font-family: var(--font-mono); font-size: 11px; letter-spacing: 0.1em;
  text-transform: uppercase; color: var(--ink-faint);
  border-top: 1px solid var(--paper-dark); padding-top: 10px; z-index: 2;
}
.slide.dark .chrome { color: var(--paper-dark); border-color: rgba(221,210,182,0.25); }
.chrome .star { color: var(--mustard); margin-right: 0.4em; }
.chrome .pg { font-variant-numeric: tabular-nums; }

/* inner column */
.col { position: relative; z-index: 1; height: 100%; display: flex; flex-direction: column; padding-bottom: 40px; }

.eyebrow {
  font-family: var(--font-mono); font-size: 12px; letter-spacing: 0.16em;
  text-transform: uppercase; color: var(--ink-mute); margin-bottom: 18px;
  border-bottom: 1px solid var(--coral); padding-bottom: 4px; display: inline-block; align-self: flex-start;
}
.slide.dark .eyebrow { color: var(--paper-dark); border-color: var(--coral); }

h1.cover-title {
  font-family: var(--font-display); font-weight: 800; font-size: 92px; line-height: 0.96;
  letter-spacing: -0.04em; color: inherit;
}
h1.cover-title em { font-family: var(--font-serif); font-style: italic; font-weight: 500; letter-spacing: -0.02em; }
.cover-title .em { color: var(--coral); }

.cover-zh {
  font-family: var(--font-serif); font-style: italic; font-weight: 500;
  font-size: 30px; line-height: 1.3; color: var(--ink-soft); margin-top: 22px; max-width: 28ch;
}
.slide.dark .cover-zh { color: var(--paper-dark); }

h2.title {
  font-family: var(--font-display); font-weight: 800; font-size: 56px; line-height: 1.05;
  letter-spacing: -0.025em; max-width: 22ch; margin-bottom: 8px;
}
h2.title em { font-family: var(--font-serif); font-style: italic; font-weight: 500; color: var(--coral); }
.title-en { font-family: var(--font-serif); font-style: italic; font-weight: 500; font-size: 22px; color: var(--ink-mute); margin-bottom: 24px; max-width: 50ch; }

.bilingual { display: grid; grid-template-columns: 1fr 1fr; gap: 56px; flex: 1; align-content: start; }
.bilingual h3 { font-family: var(--font-mono); font-size: 11px; letter-spacing: 0.16em; text-transform: uppercase; color: var(--ink-faint); margin-bottom: 14px; }
.bilingual .lang-zh { font-size: 18px; line-height: 1.55; color: var(--ink-soft); }
.bilingual .lang-en { font-family: var(--font-serif); font-size: 17px; line-height: 1.5; color: var(--ink-soft); font-style: normal; font-weight: 500; }
.bilingual p { margin-bottom: 12px; }
.bilingual ul { padding-left: 1.2em; margin-top: 6px; }
.bilingual li { margin-bottom: 8px; line-height: 1.5; }

.roman {
  font-family: var(--font-serif); font-style: italic; font-weight: 500;
  color: var(--coral); font-size: 18px; letter-spacing: 0.04em;
}
.chapter-num {
  font-family: var(--font-serif); font-style: italic; font-weight: 500;
  font-size: 220px; line-height: 1; color: var(--coral); letter-spacing: -0.03em;
}

/* stats slide */
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 28px; margin-top: 28px; }
.stat .val {
  font-family: var(--font-serif); font-style: italic; font-weight: 500;
  font-size: 78px; line-height: 1; letter-spacing: -0.02em; color: var(--coral);
  font-variant-numeric: tabular-nums;
}
.stat .lbl { font-family: var(--font-mono); font-size: 11px; letter-spacing: 0.14em; text-transform: uppercase; color: var(--ink-mute); margin-top: 10px; }
.stat .sub { font-size: 14px; color: var(--ink-soft); margin-top: 6px; line-height: 1.4; }

/* method cards */
.methods { display: grid; grid-template-columns: 1fr 1fr; gap: 24px 36px; margin-top: 18px; }
.method { border-left: 2px solid var(--coral); padding: 6px 0 6px 18px; }
.method .name { font-family: var(--font-display); font-weight: 700; font-size: 19px; letter-spacing: -0.01em; }
.method .meta { font-family: var(--font-mono); font-size: 10px; letter-spacing: 0.14em; text-transform: uppercase; color: var(--ink-faint); margin-top: 2px; }
.method .body { font-size: 14.5px; color: var(--ink-soft); margin-top: 8px; line-height: 1.55; }

/* arch image slide */
.arch-figure { display: grid; grid-template-columns: 1fr 1.3fr; gap: 40px; flex: 1; align-items: center; }
.arch-figure img { width: 100%; height: auto; border: 1px solid var(--paper-dark); background: var(--bone); }
.arch-figure .caption { font-family: var(--font-mono); font-size: 11px; letter-spacing: 0.12em; text-transform: uppercase; color: var(--ink-faint); margin-top: 10px; }
.arch-figure .arch-text { font-size: 16px; line-height: 1.55; color: var(--ink-soft); }
.arch-figure .arch-text strong { color: var(--ink); font-weight: 700; }

/* limits / takeaways */
.list-pair { display: grid; grid-template-columns: 1fr 1fr; gap: 32px 56px; }
.list-pair h3 {
  font-family: var(--font-mono); font-size: 11px; letter-spacing: 0.16em;
  text-transform: uppercase; color: var(--ink-faint); margin-bottom: 14px;
  border-bottom: 1px solid var(--paper-dark); padding-bottom: 6px;
}
.list-pair li { margin-bottom: 10px; line-height: 1.5; font-size: 16px; color: var(--ink-soft); }

/* end slide */
.end-mega {
  font-family: var(--font-serif); font-style: italic; font-weight: 500;
  font-size: 200px; line-height: 0.95; letter-spacing: -0.04em; color: var(--coral);
}
.end-colophon {
  margin-top: 60px; font-family: var(--font-mono); font-size: 13px;
  letter-spacing: 0.1em; text-transform: uppercase; color: var(--paper-dark);
}

/* nav */
.nav-dots {
  position: fixed; bottom: 18px; left: 50%; transform: translateX(-50%);
  display: flex; gap: 8px; z-index: 50;
}
.nav-dots button {
  width: 7px; height: 7px; border-radius: 50%; background: var(--paper-dark);
  border: none; cursor: pointer; transition: background 0.2s, transform 0.2s;
}
.nav-dots button[aria-current="true"] { background: var(--coral); transform: scale(1.4); }
.help {
  position: fixed; bottom: 18px; right: 24px; font-family: var(--font-mono);
  font-size: 10px; color: var(--ink-faint); letter-spacing: 0.1em; text-transform: uppercase; z-index: 50;
}
.portfolio-exit {
  position: fixed; top: 12px; right: 16px; z-index: 100;
  display: flex; gap: 4px; padding: 4px;
  background: rgba(21, 20, 15, 0.92); border: 1px solid rgba(239, 231, 210, 0.32);
  font-family: var(--font-mono); font-size: 11px; letter-spacing: 0.05em;
}
.portfolio-exit a {
  min-height: 44px; display: inline-flex; align-items: center; padding: 0 10px;
  color: var(--paper); text-decoration: none;
}
.portfolio-exit a:hover,
.portfolio-exit a:focus-visible { color: var(--ink); background: var(--mustard); outline: none; }

/* overview grid */
.deck.overview .deck-track { display: grid; grid-template-columns: repeat(4, 1fr); transform: none !important; gap: 20px; padding: 40px; width: 100%; height: 100vh; }
.deck.overview .slide { width: 100%; height: 220px; transform: scale(1); cursor: pointer; outline: 2px solid transparent; }
.deck.overview .slide:hover { outline-color: var(--coral); }
.deck.overview .chrome, .deck.overview .nav-dots, .deck.overview .help { display: none; }
.deck.overview .slide * { font-size: 0.4em !important; }
.deck.overview .slide .chapter-num, .deck.overview .slide .end-mega { font-size: 60px !important; }
.deck.overview .slide .cover-title { font-size: 28px !important; }

@media (prefers-reduced-motion: reduce) {
  .deck-track { transition: none; }
  .nav-dots button { transform: none; transition: background-color 0.18s cubic-bezier(0.23,1,0.32,1); }
  .nav-dots button[aria-current="true"] { transform: none; }
}

@media print {
  html, body { background: white; overflow: visible; }
  body { display: block; }
  .deck, .deck-track { width: auto !important; height: auto !important; transform: none !important; display: block !important; }
  .slide { page-break-after: always; transform: none !important; box-shadow: none; }
  .nav-dots, .help, .portfolio-exit { display: none; }
}