/* =================================================================
   three.js 中文展示页 — Editorial Index × Engineering Brutalism
   ================================================================= */

/* ---------- Design Tokens ---------- */
:root {
  --paper: #f6f3ec;
  --paper-deep: #ebe5d6;
  --ink: #181816;
  --ink-soft: #2a2a28;
  --vermilion: #c2410c;
  --vermilion-soft: #ea580c;
  --mist: #a8a29e;
  --line: rgba(24, 24, 22, 0.18);
  --line-soft: rgba(24, 24, 22, 0.08);

  --font-display: "Fraunces", "Noto Serif SC", Georgia, serif;
  --font-body: "Inter Tight", "Noto Serif SC", -apple-system, "Helvetica Neue", Arial, sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", Menlo, Consolas, monospace;
  --font-cn: "Noto Serif SC", "Songti SC", "STSong", serif;

  --r-sm: 4px;
  --r-md: 8px;
  --r-lg: 12px;

  --gutter: clamp(20px, 4vw, 56px);
  --max: 1320px;

  --ease: cubic-bezier(0.2, 0.7, 0.2, 1);
}

/* ---------- Reset ---------- */
*,
*::before,
*::after {
  box-sizing: border-box;
}
html,
body {
  margin: 0;
  padding: 0;
}
html {
  scroll-behavior: smooth;
}
body {
  font-family: var(--font-body);
  font-feature-settings: "ss01", "cv11";
  background: var(--paper);
  color: var(--ink);
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
  /* layered radial vignette + paper warmth */
  background-image:
    radial-gradient(1200px 600px at 12% -10%, rgba(194, 65, 12, 0.06), transparent 60%),
    radial-gradient(900px 500px at 95% 0%, rgba(24, 24, 22, 0.05), transparent 60%),
    radial-gradient(1400px 800px at 50% 110%, rgba(24, 24, 22, 0.04), transparent 60%);
}
a {
  color: inherit;
  text-decoration: none;
}
img,
svg,
canvas {
  display: block;
}
button {
  font: inherit;
  cursor: pointer;
}

/* ---------- Paper grain ---------- */
.grain {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 1000;
  opacity: 0.35;
  mix-blend-mode: multiply;
  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='160' height='160'><filter id='n'><feTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='2' stitchTiles='stitch'/><feColorMatrix values='0 0 0 0 0.09 0 0 0 0 0.09 0 0 0 0 0.09 0 0 0 0.5 0'/></filter><rect width='100%' height='100%' filter='url(%23n)'/></svg>");
}

/* ---------- Top bar ---------- */
.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(246, 243, 236, 0.85);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line-soft);
}
.topbar__inner {
  max-width: var(--max);
  margin: 0 auto;
  padding: 14px var(--gutter);
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 32px;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 20px;
  letter-spacing: -0.01em;
  color: var(--ink);
}
.brand__mark {
  display: inline-grid;
  place-items: center;
  color: var(--ink);
}
.brand__dot {
  color: var(--vermilion);
}
.nav {
  display: flex;
  gap: 28px;
  justify-content: center;
  font-size: 14px;
  color: var(--ink-soft);
}
.nav a {
  position: relative;
  padding: 4px 0;
  transition: color 0.2s var(--ease);
}
.nav a::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 1px;
  background: var(--vermilion);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.3s var(--ease);
}
.nav a:hover {
  color: var(--ink);
}
.nav a:hover::after {
  transform: scaleX(1);
}
.topbar__meta {
  font-size: 12px;
  color: var(--mist);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

@media (max-width: 760px) {
  .topbar__inner {
    grid-template-columns: auto auto;
    gap: 16px;
  }
  .nav {
    display: none;
  }
}

/* ---------- Typography helpers ---------- */
.mono {
  font-family: var(--font-mono);
  letter-spacing: 0.01em;
}
.dim {
  color: var(--mist);
}
.eyebrow {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--vermilion);
  margin: 0 0 12px;
}
.display {
  font-family: var(--font-display);
  font-weight: 400;
  font-variation-settings: "opsz" 144;
  font-size: clamp(48px, 7.2vw, 96px);
  line-height: 0.98;
  letter-spacing: -0.025em;
  margin: 0 0 28px;
  color: var(--ink);
}
.display em {
  font-style: italic;
  font-weight: 500;
  color: var(--vermilion);
  position: relative;
}
.display em::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0.08em;
  height: 0.06em;
  background: var(--vermilion);
  opacity: 0.18;
  z-index: -1;
}
.lede {
  font-family: var(--font-cn);
  font-size: clamp(16px, 1.4vw, 19px);
  line-height: 1.65;
  color: var(--ink-soft);
  max-width: 52ch;
  margin: 0 0 32px;
}
.section-title {
  font-family: var(--font-display);
  font-weight: 400;
  font-variation-settings: "opsz" 96;
  font-size: clamp(32px, 4.4vw, 56px);
  line-height: 1.04;
  letter-spacing: -0.02em;
  margin: 0;
  color: var(--ink);
}
.section-sub {
  font-family: var(--font-cn);
  font-size: 16px;
  line-height: 1.65;
  color: var(--ink-soft);
  max-width: 60ch;
  margin: 12px 0 0;
}
.section-head {
  margin-bottom: 40px;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 22px;
  font-size: 14px;
  font-weight: 500;
  letter-spacing: 0.02em;
  border-radius: var(--r-md);
  border: 1px solid var(--ink);
  transition: background-color 0.2s var(--ease), color 0.2s var(--ease), transform 0.2s var(--ease);
}
.btn--primary {
  background: var(--vermilion);
  color: var(--paper);
  border-color: var(--vermilion);
}
.btn--primary:hover {
  background: var(--ink);
  border-color: var(--ink);
  color: var(--paper);
  transform: translateY(-1px);
}
.btn--ghost {
  background: transparent;
  color: var(--ink);
}
.btn--ghost:hover {
  background: var(--ink);
  color: var(--paper);
}
.link-underline {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  color: var(--ink);
  border-bottom: 1px solid var(--vermilion);
  padding-bottom: 2px;
  transition: gap 0.2s var(--ease);
}
.link-underline:hover {
  gap: 10px;
}

/* ---------- Hero ---------- */
.hero {
  max-width: var(--max);
  margin: 0 auto;
  padding: clamp(56px, 10vh, 120px) var(--gutter) 0;
}
.hero__grid {
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: clamp(32px, 5vw, 80px);
  align-items: center;
  min-height: 70vh;
}
.hero__stage {
  position: relative;
  aspect-ratio: 1 / 1;
  max-width: 520px;
  margin: 0 auto;
  width: 100%;
}
#hero-canvas {
  width: 100%;
  height: 100%;
  cursor: grab;
}
#hero-canvas:active {
  cursor: grabbing;
}
.hero__caption {
  position: absolute;
  bottom: -32px;
  left: 0;
  font-size: 11px;
  color: var(--mist);
  letter-spacing: 0.16em;
  text-transform: uppercase;
}
.hero__caption::before {
  content: "›";
  color: var(--vermilion);
  margin-right: 6px;
}
.hero__cta {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}
.rule {
  height: 1px;
  background: var(--ink);
  margin-top: clamp(56px, 9vh, 100px);
  opacity: 0.85;
}

@media (max-width: 880px) {
  .hero__grid {
    grid-template-columns: 1fr;
  }
  .hero__stage {
    max-width: 360px;
  }
}

/* ---------- Section spacing ---------- */
section {
  max-width: var(--max);
  margin: 0 auto;
  padding: clamp(64px, 10vh, 120px) var(--gutter);
}

/* ---------- Showcase ---------- */
.showcase__grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}
.demo {
  position: relative;
  background: var(--ink);
  color: var(--paper);
  border-radius: var(--r-lg);
  overflow: hidden;
  border: 1px solid var(--ink);
  min-height: 360px;
  display: flex;
  flex-direction: column;
  isolation: isolate;
  transition: transform 0.4s var(--ease);
}
.demo:hover {
  transform: translateY(-3px);
}
.demo__stage {
  position: relative;
  flex: 1 1 auto;
  min-height: 240px;
  overflow: hidden;
}
.demo__canvas {
  display: block;
  width: 100%;
  height: 100%;
}
.demo__placeholder {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--mist);
  letter-spacing: 0.16em;
  text-transform: uppercase;
}
.demo__placeholder::before {
  content: "›";
  color: var(--vermilion);
  margin-right: 6px;
}
.demo__body {
  padding: 18px 22px 22px;
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  border-top: 1px solid rgba(255, 255, 255, 0.06);
  background: var(--ink-soft);
}
.demo__heading {
  flex: 1 1 auto;
  min-width: 0;
}
.demo__no {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--vermilion-soft);
  margin: 0 0 6px;
}
.demo__title {
  font-family: var(--font-display);
  font-weight: 500;
  font-variation-settings: "opsz" 60;
  font-size: 22px;
  line-height: 1.2;
  margin: 0 0 4px;
  color: var(--paper);
  letter-spacing: -0.01em;
}
.demo__sub {
  font-family: var(--font-cn);
  font-size: 13.5px;
  line-height: 1.6;
  color: rgba(246, 243, 236, 0.65);
  margin: 0;
}
.demo__tag {
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.14em;
  color: var(--mist);
  padding: 4px 8px;
  border: 1px solid rgba(255, 255, 255, 0.14);
  border-radius: var(--r-sm);
  text-transform: uppercase;
  white-space: nowrap;
}
@media (max-width: 760px) {
  .showcase__grid {
    grid-template-columns: 1fr;
  }
  .demo {
    min-height: 320px;
  }
}

/* ---------- Features ---------- */
.features__grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0;
  border-top: 1px solid var(--line);
}
.feature {
  padding: 28px 24px 32px 0;
  border-right: 1px solid var(--line);
  position: relative;
  transition: transform 0.3s var(--ease);
}
.feature:nth-child(4n) {
  border-right: none;
  padding-right: 0;
}
.feature:not(:first-child) {
  padding-left: 24px;
}
.feature:hover {
  transform: translateY(-2px);
}
.feature__no {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--mist);
  letter-spacing: 0.12em;
  margin-bottom: 16px;
}
.feature__icon {
  width: 40px;
  height: 40px;
  display: grid;
  place-items: center;
  color: var(--ink);
  margin-bottom: 18px;
}
.feature__title {
  font-family: var(--font-display);
  font-weight: 500;
  font-variation-settings: "opsz" 60;
  font-size: 22px;
  line-height: 1.2;
  margin: 0 0 6px;
  color: var(--ink);
}
.feature__title-en {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--vermilion);
  margin-bottom: 12px;
  letter-spacing: 0.06em;
}
.feature__desc {
  font-family: var(--font-cn);
  font-size: 14.5px;
  line-height: 1.7;
  color: var(--ink-soft);
  margin: 0;
}

@media (max-width: 980px) {
  .features__grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .feature {
    border-right: 1px solid var(--line);
    border-bottom: 1px solid var(--line);
    padding: 24px 16px 28px 0;
  }
  .feature:nth-child(2n) {
    border-right: none;
    padding-right: 0;
  }
  .feature:nth-child(2n + 1) {
    padding-left: 16px;
  }
  .feature:nth-child(n + 3) {
    border-bottom: none;
  }
}
@media (max-width: 560px) {
  .features__grid {
    grid-template-columns: 1fr;
  }
  .feature {
    border-right: none;
    border-bottom: 1px solid var(--line);
    padding: 24px 0;
  }
  .feature:not(:first-child) {
    padding-left: 0;
  }
  .feature:last-child {
    border-bottom: none;
  }
}

/* ---------- Code panel ---------- */
.code__panel {
  margin: 0;
  background: var(--ink-soft);
  color: #e6e2d8;
  border-radius: var(--r-lg);
  overflow: hidden;
  border: 1px solid var(--ink);
  box-shadow: 0 30px 60px -30px rgba(24, 24, 22, 0.45);
}
.code__bar {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 12px 16px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  background: #1f1f1d;
}
.dot {
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: #4a4a48;
}
.dot--r {
  background: #d97366;
}
.dot--y {
  background: #d9a566;
}
.dot--g {
  background: #88b87a;
}
.code__file {
  margin-left: 12px;
  font-size: 12px;
  color: #a8a29e;
  letter-spacing: 0.04em;
}
.code__copy {
  margin-left: auto;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: transparent;
  border: 1px solid rgba(255, 255, 255, 0.18);
  color: #e6e2d8;
  padding: 6px 12px;
  font-size: 12px;
  border-radius: var(--r-sm);
  letter-spacing: 0.04em;
  transition: background 0.2s var(--ease), color 0.2s var(--ease);
}
.code__copy:hover {
  background: var(--vermilion);
  border-color: var(--vermilion);
  color: var(--paper);
}
.code__copy.is-copied {
  background: #88b87a;
  border-color: #88b87a;
  color: var(--ink);
}
.code__body {
  margin: 0;
  padding: 24px 28px 28px;
  font-family: var(--font-mono);
  font-size: 13.5px;
  line-height: 1.7;
  overflow-x: auto;
  white-space: pre;
  color: #e6e2d8;
  tab-size: 2;
}
.code__body .tk-c {
  color: #a8a29e;
  font-style: italic;
}
.code__body .tk-k {
  color: #d97366;
}
.code__body .tk-s {
  color: #88b87a;
}
.code__body .tk-n {
  color: #d9a566;
}
.code__body .tk-f {
  color: #ea580c;
}
.code__meta {
  padding: 14px 24px;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  background: #1f1f1d;
  display: flex;
  justify-content: flex-end;
  align-items: center;
}
.code__meta .link-underline {
  color: #e6e2d8;
  border-color: var(--vermilion-soft);
}

/* ---------- Resources ---------- */
.resources__grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0;
  border-top: 1px solid var(--ink);
  border-left: 1px solid var(--ink);
}
.res {
  padding: 28px 24px 32px;
  border-right: 1px solid var(--ink);
  border-bottom: 1px solid var(--ink);
  background: var(--paper);
  transition: background 0.25s var(--ease), color 0.25s var(--ease);
  display: flex;
  flex-direction: column;
  gap: 14px;
  min-height: 220px;
  position: relative;
}
.res:hover {
  background: var(--ink);
  color: var(--paper);
}
.res:hover .res__no,
.res:hover .res__sub {
  color: rgba(246, 243, 236, 0.7);
}
.res:hover .res__icon {
  color: var(--vermilion-soft);
}
.res:hover .res__arrow {
  transform: translate(2px, -2px);
  color: var(--vermilion-soft);
}
.res__no {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--vermilion);
}
.res__icon {
  width: 28px;
  height: 28px;
  color: var(--ink);
  transition: color 0.25s var(--ease);
}
.res__title {
  font-family: var(--font-display);
  font-weight: 500;
  font-variation-settings: "opsz" 60;
  font-size: 24px;
  line-height: 1.15;
  margin: 0;
  letter-spacing: -0.01em;
}
.res__sub {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--mist);
  letter-spacing: 0.04em;
  margin-top: auto;
  display: flex;
  align-items: center;
  gap: 6px;
}
.res__arrow {
  display: inline-block;
  transition: transform 0.25s var(--ease), color 0.25s var(--ease);
}
@media (max-width: 980px) {
  .resources__grid {
    grid-template-columns: repeat(2, 1fr);
  }
}
@media (max-width: 560px) {
  .resources__grid {
    grid-template-columns: 1fr;
  }
}

/* ---------- CTA ---------- */
.cta__panel {
  position: relative;
  background: var(--ink);
  color: var(--paper);
  border-radius: var(--r-lg);
  padding: 36px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  border: 1px solid var(--ink);
  overflow: hidden;
}
.cta__panel::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(400px 200px at 0% 100%, rgba(194, 65, 12, 0.25), transparent 60%),
    radial-gradient(500px 240px at 100% 0%, rgba(234, 88, 12, 0.18), transparent 60%);
  pointer-events: none;
}
.cta__command {
  position: relative;
  margin: 0;
  font-size: clamp(14px, 1.5vw, 18px);
  color: var(--paper);
  white-space: pre-wrap;
  word-break: break-all;
  font-family: var(--font-mono);
}
.cta__command .prompt {
  color: var(--vermilion-soft);
  margin-right: 12px;
  user-select: none;
}
.cta__panel .code__copy--solid {
  position: relative;
  background: var(--vermilion);
  border-color: var(--vermilion);
  color: var(--paper);
}
.cta__panel .code__copy--solid:hover {
  background: var(--paper);
  color: var(--ink);
  border-color: var(--paper);
}
.cta__badges {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 20px;
}
.badge {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 10px 16px;
  background: var(--paper-deep);
  color: var(--ink);
  border: 1px solid var(--ink);
  border-radius: var(--r-sm);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  transition: background 0.2s var(--ease), color 0.2s var(--ease);
}
.badge__v {
  color: var(--vermilion);
  font-weight: 500;
}
.badge:hover {
  background: var(--ink);
  color: var(--paper);
}
.badge:hover .badge__v {
  color: var(--vermilion-soft);
}

@media (max-width: 720px) {
  .cta__panel {
    flex-direction: column;
    align-items: flex-start;
    padding: 28px 24px;
  }
}

/* ---------- Footer ---------- */
.footer {
  border-top: 1px solid var(--line);
  background: var(--paper);
}
.footer__inner {
  max-width: var(--max);
  margin: 0 auto;
  padding: 56px var(--gutter) 48px;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
}
.footer__col p.eyebrow {
  margin: 0 0 14px;
}
.footer__col a {
  display: block;
  font-size: 14px;
  padding: 4px 0;
  color: var(--ink-soft);
  transition: color 0.2s var(--ease);
}
.footer__col a:hover {
  color: var(--vermilion);
}
.footer__col--end p {
  margin: 0 0 6px;
  font-size: 12px;
  line-height: 1.7;
}
@media (max-width: 760px) {
  .footer__inner {
    grid-template-columns: 1fr;
  }
}

/* ---------- Reveal animation ---------- */
[data-reveal] {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.8s var(--ease), transform 0.8s var(--ease);
}
[data-reveal].is-visible {
  opacity: 1;
  transform: translateY(0);
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    transition-duration: 0.001ms !important;
  }
  [data-reveal] {
    opacity: 1;
    transform: none;
  }
  html {
    scroll-behavior: auto;
  }
}

/* ---------- Selection ---------- */
::selection {
  background: var(--vermilion);
  color: var(--paper);
}

/* ---------- Scrollbar (subtle) ---------- */
.code__body::-webkit-scrollbar {
  height: 8px;
}
.code__body::-webkit-scrollbar-track {
  background: transparent;
}
.code__body::-webkit-scrollbar-thumb {
  background: rgba(255, 255, 255, 0.18);
  border-radius: 4px;
}
.code__body::-webkit-scrollbar-thumb:hover {
  background: rgba(255, 255, 255, 0.32);
}