/* ==========================================================================
   AB体育官网 · 共享样式 /assets/site.css
   语言：框景横栏 + 纵向色带长卷 + 玻璃索引层与实色内容层并置
   ========================================================================== */

/* 1. Reset
   ========================================================================== */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body { margin: 0; }
img, svg, video, canvas { display: block; max-width: 100%; }
ul, ol { margin: 0; padding: 0; list-style: none; }
button { font: inherit; color: inherit; background: none; border: 0; padding: 0; cursor: pointer; }
a { color: inherit; text-decoration: none; }
h1, h2, h3, h4, h5, p, figure, blockquote { margin: 0; }
table { border-collapse: collapse; width: 100%; }

/* 2. Tokens
   ========================================================================== */
:root {
  --c-grass: #0E7A4F;
  --c-grass-deep: #0A5537;
  --c-orange: #FF6A1A;
  --c-cyan: #19E3D1;
  --c-ink: #0B1B2B;
  --c-ink-2: #142A3F;
  --c-white: #F7FAF8;
  --c-mist: #E3E9E6;
  --c-graphite: #6B7A82;
  --c-coral: #FF3D5A;

  --font-sans: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: "JetBrains Mono", "Roboto Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, "Courier New", monospace;

  --container: 1200px;
  --container-wide: 1440px;
  --container-narrow: 880px;

  --header-h: 78px;
  --header-h-compact: 62px;
  --gutter: clamp(16px, 3vw, 32px);
  --ease: cubic-bezier(.2, .7, .3, 1);

  --on-dark: rgba(247, 250, 248, .74);
  --on-dark-strong: rgba(247, 250, 248, .95);
  --line-dark: rgba(227, 233, 230, .18);
}

/* 3. Base
   ========================================================================== */
body {
  background: var(--c-white);
  color: var(--c-ink);
  font-family: var(--font-sans);
  font-size: 17px;
  line-height: 1.8;
  letter-spacing: .01em;
  -webkit-font-smoothing: antialiased;
}
@media (min-width: 1200px) { body { font-size: 18px; } }

::selection { background: var(--c-cyan); color: var(--c-ink); }

:focus-visible { outline: 2px solid var(--c-cyan); outline-offset: 3px; }

#main-content { display: block; }
#main-content:focus { outline: none; }
section[id], [data-chapter] { scroll-margin-top: calc(var(--header-h) + 24px); }

h1, h2, h3 { text-wrap: balance; }

p { max-width: 68ch; }
p + p { margin-top: .9em; }

.mono {
  font-family: var(--font-mono);
  font-feature-settings: "tnum" 1;
  letter-spacing: .08em;
}

.visually-hidden {
  position: absolute;
  width: 1px; height: 1px;
  margin: -1px; padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  clip-path: inset(50%);
  white-space: nowrap;
}

/* 4. Layout primitives
   ========================================================================== */
.shell {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding-left: var(--gutter);
  padding-right: var(--gutter);
}
.shell--narrow { max-width: var(--container-narrow); }
.shell--wide { max-width: var(--container-wide); }

.section { position: relative; padding: clamp(48px, 7vw, 96px) 0; }
.section--tight { padding: clamp(32px, 4.5vw, 60px) 0; }

.band--white { background: var(--c-white); color: var(--c-ink); }
.band--mist { background: var(--c-mist); color: var(--c-ink); }
.band--grass { background: var(--c-grass); color: var(--c-white); }
.band--grass-deep { background: var(--c-grass-deep); color: var(--c-white); }
.band--ink { background: var(--c-ink); color: var(--c-white); }

.band--field { position: relative; overflow: hidden; }
.band--field::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: 0;
  height: 240px;
  z-index: 0;
  pointer-events: none;
  background:
    radial-gradient(120% 100% at 8% 100%, rgba(14, 122, 79, .32), transparent 62%),
    radial-gradient(90% 100% at 58% 100%, rgba(14, 122, 79, .22), transparent 60%),
    radial-gradient(70% 100% at 96% 100%, rgba(25, 227, 209, .16), transparent 58%);
}
.band--field > .shell { position: relative; z-index: 1; }

.slant { position: relative; }
.slant--top { clip-path: polygon(0 2.4vw, 100% 0, 100% 100%, 0 100%); padding-top: calc(2.4vw + clamp(48px, 7vw, 96px)); }
.slant--bottom { clip-path: polygon(0 0, 100% 0, 100% calc(100% - 2.4vw), 0 100%); padding-bottom: calc(2.4vw + clamp(48px, 7vw, 96px)); }

.divider { height: 1px; border: 0; margin: 0; background: var(--c-mist); }
.ruler-strip {
  height: 8px;
  background-image: repeating-linear-gradient(90deg, rgba(107, 122, 130, .38) 0 1px, transparent 1px 20px);
}
.band--ink .ruler-strip,
.band--grass .ruler-strip,
.band--grass-deep .ruler-strip {
  background-image: repeating-linear-gradient(90deg, rgba(247, 250, 248, .3) 0 1px, transparent 1px 20px);
}

.stack { display: flex; flex-direction: column; gap: clamp(12px, 1.6vw, 20px); }
.row { display: flex; flex-wrap: wrap; align-items: center; gap: clamp(10px, 1.6vw, 18px); }

/* 5. Type scale
   ========================================================================== */
.section__head {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: 14px 28px;
  margin-bottom: clamp(20px, 3vw, 38px);
}
.section__index {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .2em;
  color: var(--c-orange);
}
.band--ink .section__index,
.band--grass .section__index,
.band--grass-deep .section__index { color: var(--c-cyan); }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .2em;
  color: var(--c-graphite);
}
.eyebrow::before { content: ""; width: 26px; height: 1px; background: currentColor; }

.display {
  font-weight: 200;
  font-size: clamp(2.4rem, 6.2vw, 5.6rem);
  line-height: 1.05;
  letter-spacing: .01em;
}
.h2 { font-weight: 900; font-size: clamp(1.5rem, 2.7vw, 2.05rem); line-height: 1.28; }
.h3 { font-weight: 900; font-size: clamp(1.12rem, 1.8vw, 1.4rem); line-height: 1.45; }
.lede { font-size: clamp(1rem, 1.3vw, 1.12rem); line-height: 1.9; color: var(--c-graphite); max-width: 56ch; }
.band--ink .lede,
.band--grass .lede,
.band--grass-deep .lede { color: var(--on-dark); }

.text-accent { color: var(--c-orange); }
.text-cyan { color: var(--c-cyan); }
.text-grass { color: var(--c-grass); }

/* 6. Grid
   ========================================================================== */
.grid { display: grid; gap: clamp(16px, 2.4vw, 28px); }
.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid--12 { grid-template-columns: repeat(12, minmax(0, 1fr)); }
.col-4 { grid-column: span 4; }
.col-5 { grid-column: span 5; }
.col-6 { grid-column: span 6; }
.col-7 { grid-column: span 7; }
.col-8 { grid-column: span 8; }
.col-12 { grid-column: span 12; }

/* 7. Surfaces
   ========================================================================== */
.card {
  position: relative;
  background: var(--c-white);
  border: 1px solid var(--c-mist);
  border-radius: 2px;
  padding: clamp(18px, 2.2vw, 26px);
  transition: transform .18s var(--ease), border-color .18s var(--ease), box-shadow .18s var(--ease);
}
.card::before {
  content: "";
  position: absolute;
  left: 0; top: 0; bottom: 0;
  width: 3px;
  background: var(--c-cyan);
  transform: scaleY(0);
  transform-origin: top center;
  transition: transform .18s var(--ease);
}
.card:hover {
  transform: translateY(-2px);
  border-color: rgba(25, 227, 209, .6);
  box-shadow: 0 18px 36px -28px rgba(11, 27, 43, .65);
}
.card:hover::before { transform: scaleY(1); }
.card__title { font-weight: 900; font-size: 1.1rem; line-height: 1.4; }
.card__meta {
  margin-top: 6px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .1em;
  color: var(--c-graphite);
}
.card--ink { background: var(--c-ink); border-color: var(--line-dark); color: var(--c-white); }
.card--ink .card__meta { color: var(--on-dark); }
.card--glass {
  background: rgba(20, 42, 63, .55);
  border-color: var(--line-dark);
  color: var(--c-white);
  -webkit-backdrop-filter: blur(12px) saturate(140%);
  backdrop-filter: blur(12px) saturate(140%);
}

.glass {
  background: rgba(20, 42, 63, .5);
  border: 1px solid var(--line-dark);
  color: var(--c-white);
  -webkit-backdrop-filter: blur(14px) saturate(140%);
  backdrop-filter: blur(14px) saturate(140%);
}
.panel { background: var(--c-white); border: 1px solid var(--c-mist); padding: clamp(18px, 2.4vw, 30px); }
.panel--framed { position: relative; border: 1px solid var(--c-ink); }
.panel--framed::before {
  content: "";
  position: absolute;
  inset: 6px;
  border: 1px dashed rgba(107, 122, 130, .38);
  pointer-events: none;
}

.tick-frame { position: relative; border: 1px solid rgba(11, 27, 43, .22); padding: clamp(18px, 3vw, 34px); color: var(--c-orange); }
.band--ink .tick-frame,
.band--grass .tick-frame { border-color: var(--line-dark); color: var(--c-cyan); }
.tick-frame::before {
  content: "";
  position: absolute;
  inset: -1px;
  pointer-events: none;
  background:
    linear-gradient(currentColor, currentColor) left top / 14px 2px no-repeat,
    linear-gradient(currentColor, currentColor) left top / 2px 14px no-repeat,
    linear-gradient(currentColor, currentColor) right top / 14px 2px no-repeat,
    linear-gradient(currentColor, currentColor) right top / 2px 14px no-repeat,
    linear-gradient(currentColor, currentColor) left bottom / 14px 2px no-repeat,
    linear-gradient(currentColor, currentColor) left bottom / 2px 14px no-repeat,
    linear-gradient(currentColor, currentColor) right bottom / 14px 2px no-repeat,
    linear-gradient(currentColor, currentColor) right bottom / 2px 14px no-repeat;
}
.tick-frame > * { position: relative; z-index: 1; }

/* 8. Chips / tags / stats
   ========================================================================== */
.chip-row { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 7px 15px;
  border: 1px solid rgba(11, 27, 43, .22);
  border-radius: 999px;
  font-size: .82rem;
  font-weight: 700;
  letter-spacing: .06em;
  color: var(--c-ink);
  transition: background-color .18s var(--ease), color .18s var(--ease), border-color .18s var(--ease);
}
.chip:hover { border-color: var(--c-grass); color: var(--c-grass); }
.chip[aria-pressed="true"] { background: var(--c-grass); border-color: var(--c-grass); color: var(--c-white); }
.chip--accent[aria-pressed="true"] { background: var(--c-orange); border-color: var(--c-orange); color: var(--c-ink); }
.chip--glass { border-color: rgba(247, 250, 248, .34); color: var(--on-dark-strong); }
.chip--glass:hover { border-color: var(--c-cyan); color: var(--c-cyan); }
.chip--glass[aria-pressed="true"] { background: var(--c-cyan); border-color: var(--c-cyan); color: var(--c-ink); }

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 9px;
  border: 1px solid currentColor;
  border-radius: 2px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .14em;
  text-transform: uppercase;
}
.tag--cyan { color: var(--c-cyan); }
.tag--orange { color: var(--c-orange); }
.tag--grass { color: var(--c-grass); }
.tag--coral { color: var(--c-coral); }

.stat { display: flex; flex-direction: column; gap: 4px; }
.stat__value {
  font-family: var(--font-mono);
  font-size: clamp(1.7rem, 3.4vw, 2.6rem);
  line-height: 1;
  letter-spacing: .02em;
  color: var(--c-grass);
}
.band--ink .stat__value,
.band--grass .stat__value,
.band--grass-deep .stat__value { color: var(--c-cyan); }
.stat__label { font-size: 12px; letter-spacing: .14em; color: var(--c-graphite); }
.band--ink .stat__label,
.band--grass .stat__label { color: var(--on-dark); }

/* 9. Index lists & chapter index
   ========================================================================== */
.index-list { display: flex; flex-direction: column; border-top: 1px solid var(--c-mist); }
.index-list__item {
  display: grid;
  grid-template-columns: 56px minmax(0, 1fr) auto;
  align-items: baseline;
  gap: 12px;
  padding: 14px 4px;
  border-bottom: 1px solid var(--c-mist);
  transition: background-color .18s var(--ease);
}
.index-list__item:hover { background: rgba(25, 227, 209, .08); }
.index-list__num { font-family: var(--font-mono); font-size: 12px; letter-spacing: .12em; color: var(--c-orange); }
.index-list__label { font-weight: 700; }
.index-list__meta { font-family: var(--font-mono); font-size: 12px; letter-spacing: .08em; color: var(--c-graphite); }
.band--ink .index-list,
.band--ink .index-list__item { border-color: var(--line-dark); }
.band--ink .index-list__meta { color: var(--on-dark); }

.chapter-index {
  position: sticky;
  top: calc(var(--header-h) + 18px);
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.chapter-index__link {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr);
  gap: 10px;
  align-items: center;
  padding: 8px 10px;
  border-left: 2px solid transparent;
  font-size: .86rem;
  color: var(--c-graphite);
  transition: color .18s var(--ease), border-color .18s var(--ease), background-color .18s var(--ease);
}
.chapter-index__link:hover { color: var(--c-ink); background: rgba(25, 227, 209, .08); }
.chapter-index__link.is-active { color: var(--c-grass); border-left-color: var(--c-orange); font-weight: 700; }

/* 10. Accordion
   ========================================================================== */
.accordion { display: flex; flex-direction: column; border-top: 1px solid var(--c-mist); }
.accordion__item { border-bottom: 1px solid var(--c-mist); }
.accordion__trigger {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 18px 4px;
  text-align: left;
  font-size: 1.02rem;
  font-weight: 700;
  letter-spacing: .01em;
  transition: color .18s var(--ease);
}
.accordion__trigger:hover { color: var(--c-grass); }
.accordion__icon { position: relative; flex: 0 0 auto; width: 14px; height: 14px; }
.accordion__icon::before,
.accordion__icon::after {
  content: "";
  position: absolute;
  background: var(--c-orange);
  transition: transform .2s var(--ease);
}
.accordion__icon::before { left: 0; right: 0; top: 6px; height: 2px; }
.accordion__icon::after { top: 0; bottom: 0; left: 6px; width: 2px; }
.accordion__item[data-open] .accordion__icon::after { transform: scaleY(0); }
.accordion__panel {
  display: none;
  padding: 0 4px 22px;
  max-width: 68ch;
  color: var(--c-graphite);
}
.accordion__item[data-open] .accordion__panel { display: block; animation: panel-in .28s var(--ease); }
@keyframes panel-in { from { opacity: 0; transform: translateY(-6px); } to { opacity: 1; transform: none; } }
.band--ink .accordion,
.band--ink .accordion__item { border-color: var(--line-dark); }
.band--ink .accordion__panel { color: var(--on-dark); }

/* 11. Timeline
   ========================================================================== */
.timeline { position: relative; padding-left: 26px; }
.timeline::before {
  content: "";
  position: absolute;
  left: 6px; top: 8px; bottom: 8px;
  width: 2px;
  background: linear-gradient(180deg, var(--c-grass), var(--c-cyan));
}
.timeline__item { position: relative; padding-bottom: 26px; }
.timeline__node {
  position: absolute;
  left: -26px; top: 7px;
  width: 14px; height: 14px;
  border-radius: 50%;
  background: var(--c-ink);
  border: 2px solid var(--c-cyan);
}
.timeline__item--new .timeline__node { border-color: var(--c-coral); box-shadow: 0 0 0 4px rgba(255, 61, 90, .18); }
.timeline__date { font-family: var(--font-mono); font-size: 12px; letter-spacing: .12em; color: var(--c-orange); }

/* 12. Media containers
   ========================================================================== */
.media {
  position: relative;
  overflow: hidden;
  background: var(--c-ink-2);
  border: 1px solid var(--c-mist);
  border-radius: 2px;
}
.media__img { width: 100%; height: 100%; object-fit: cover; }
.media--hero { aspect-ratio: 21 / 9; }
.media--wide { aspect-ratio: 16 / 9; }
.media--square { aspect-ratio: 1 / 1; }
.media--tall { aspect-ratio: 3 / 4; }
.media__caption {
  position: absolute;
  left: 0; right: 0; bottom: 0;
  padding: 14px 16px 12px;
  background: linear-gradient(180deg, transparent, rgba(11, 27, 43, .86));
  color: var(--c-white);
  font-size: 12px;
  letter-spacing: .06em;
}
.media__tag { position: absolute; left: 12px; top: 12px; }
.media--placeholder {
  background-image:
    linear-gradient(135deg, rgba(14, 122, 79, .9), rgba(11, 27, 43, .94)),
    repeating-linear-gradient(90deg, rgba(247, 250, 248, .09) 0 1px, transparent 1px 26px);
  background-size: cover, auto;
}
.media--placeholder::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: 0;
  height: 46%;
  background:
    radial-gradient(120% 100% at 18% 100%, rgba(14, 122, 79, .55), transparent 62%),
    radial-gradient(90% 100% at 72% 100%, rgba(25, 227, 209, .22), transparent 60%);
}

/* 13. Buttons
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 9px 16px;
  border: 1px solid transparent;
  border-radius: 2px;
  font-size: .86rem;
  font-weight: 700;
  letter-spacing: .06em;
  white-space: nowrap;
  transition: background-color .18s var(--ease), color .18s var(--ease), border-color .18s var(--ease), transform .18s var(--ease);
}
.btn--solid { background: var(--c-grass); border-color: var(--c-grass); color: var(--c-white); }
.btn--solid:hover { background: var(--c-grass-deep); border-color: var(--c-grass-deep); }
.btn--accent { background: var(--c-orange); border-color: var(--c-orange); color: var(--c-ink); }
.btn--accent:hover { background: #ff8339; border-color: #ff8339; }
.btn--ghost { border-color: rgba(247, 250, 248, .4); color: var(--c-white); }
.btn--ghost:hover { border-color: var(--c-cyan); color: var(--c-cyan); }
.btn--quiet {
  padding: 9px 4px;
  border: 0;
  border-bottom: 1px dashed rgba(25, 227, 209, .55);
  border-radius: 0;
  color: var(--on-dark);
}
.btn--quiet:hover { color: var(--c-cyan); }
.btn--ink { background: var(--c-ink); border-color: var(--c-ink); color: var(--c-white); }
.btn--ink:hover { background: var(--c-ink-2); }
.btn--outline-ink { border-color: rgba(11, 27, 43, .3); color: var(--c-ink); }
.btn--outline-ink:hover { border-color: var(--c-grass); color: var(--c-grass); }

/* 14. Breadcrumbs
   ========================================================================== */
.breadcrumbs { padding: 14px 0; font-size: 12px; letter-spacing: .08em; color: var(--c-graphite); }
.breadcrumbs__list { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; }
.breadcrumbs__link { font-weight: 700; color: var(--c-graphite); transition: color .18s var(--ease); }
.breadcrumbs__link:hover { color: var(--c-grass); }
.breadcrumbs__sep { font-family: var(--font-mono); color: rgba(107, 122, 130, .6); }
.breadcrumbs__current { font-weight: 700; color: var(--c-ink); }
.band--ink .breadcrumbs,
.band--ink .breadcrumbs__link { color: var(--on-dark); }
.band--ink .breadcrumbs__current { color: var(--c-white); }

/* 15. Copy field
   ========================================================================== */
.copy-field {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px 14px;
  padding: 12px 14px;
  border: 1px solid var(--c-mist);
  background: var(--c-white);
}
.copy-field__value {
  flex: 1 1 220px;
  font-family: var(--font-mono);
  font-size: .92rem;
  letter-spacing: .04em;
  color: var(--c-ink);
  word-break: break-all;
}
.copy-field__state { font-size: 12px; letter-spacing: .1em; color: var(--c-graphite); min-height: 1em; }
.copy-field[data-copied] { border-color: var(--c-grass); }
.copy-field[data-copied] .copy-field__state { color: var(--c-grass); font-weight: 700; }
.copy-field--glass { background: rgba(20, 42, 63, .5); border-color: var(--line-dark); color: var(--c-white); }
.copy-field--glass .copy-field__value { color: var(--c-white); }
.copy-field--glass .copy-field__state { color: var(--on-dark); }
.copy-field--glass[data-copied] .copy-field__state { color: var(--c-cyan); }
.copy-field__btn { flex: 0 0 auto; }

/* 16. Reveal
   ========================================================================== */
html.js [data-reveal] {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity .32s var(--ease), transform .32s var(--ease);
}
html.js [data-reveal].is-in { opacity: 1; transform: none; }

/* 17. Header — 框景横栏
   ========================================================================== */
.skip-link {
  position: absolute;
  left: 12px;
  top: -80px;
  z-index: 99;
  padding: 10px 16px;
  background: var(--c-cyan);
  color: var(--c-ink);
  border-radius: 2px;
  font-size: .85rem;
  font-weight: 700;
  transition: top .18s var(--ease);
}
.skip-link:focus { top: 12px; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  background: linear-gradient(180deg, rgba(11, 27, 43, .97), rgba(11, 27, 43, .9));
  color: var(--c-white);
  border-bottom: 1px solid var(--line-dark);
  -webkit-backdrop-filter: blur(14px) saturate(150%);
  backdrop-filter: blur(14px) saturate(150%);
}

.site-header__frame {
  position: relative;
  max-width: var(--container-wide);
  margin: 0 auto;
  padding: 0 var(--gutter);
  min-height: var(--header-h);
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: clamp(12px, 2vw, 28px);
  transition: min-height .24s var(--ease);
}
.site-header[data-stuck] .site-header__frame { min-height: var(--header-h-compact); }

.site-header__frame::before,
.site-header__frame::after {
  content: "";
  position: absolute;
  top: 0; bottom: 0;
  width: 14px;
  pointer-events: none;
  opacity: .65;
  background-image: repeating-linear-gradient(180deg, rgba(25, 227, 209, .7) 0 1px, transparent 1px 9px);
}
.site-header__frame::before { left: 0; }
.site-header__frame::after { right: 0; }

.site-header__brand { display: flex; align-items: center; gap: 12px; min-width: 0; }

.brand { display: flex; align-items: center; gap: 10px; min-width: 0; }
.brand__mark {
  flex: 0 0 auto;
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  background: var(--c-cyan);
  color: var(--c-ink);
  font-family: var(--font-mono);
  font-size: .8rem;
  font-weight: 700;
  letter-spacing: .06em;
  clip-path: polygon(0 0, 100% 0, 100% 72%, 50% 100%, 0 72%);
}
.brand__text { display: flex; flex-direction: column; line-height: 1.2; min-width: 0; }
.brand__name { font-weight: 900; font-size: 1.02rem; letter-spacing: .04em; }
.brand__line {
  font-size: 11px;
  letter-spacing: .06em;
  color: rgba(247, 250, 248, .6);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.brand__icp {
  padding-left: 10px;
  border-left: 1px solid rgba(227, 233, 230, .24);
  font-size: 11px;
  letter-spacing: .06em;
  color: rgba(247, 250, 248, .45);
}
.brand--footer .brand__mark { background: var(--c-orange); }
.brand--footer .brand__name { color: var(--c-white); }
.brand--footer .brand__line { color: var(--on-dark); }

.site-nav { justify-self: center; }
.site-nav__list { display: flex; align-items: center; gap: clamp(4px, 1.4vw, 18px); }
.site-nav__item { min-width: 0; }
.site-nav__link {
  position: relative;
  display: block;
  padding: 10px 2px;
  font-size: .92rem;
  font-weight: 500;
  letter-spacing: .06em;
  white-space: nowrap;
  color: rgba(247, 250, 248, .78);
  transition: color .18s var(--ease);
}
.site-nav__link::after {
  content: "";
  position: absolute;
  left: 0; right: 0; bottom: 2px;
  height: 2px;
  background: var(--c-cyan);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform .18s var(--ease);
}
.site-nav__link:hover { color: var(--c-white); }
.site-nav__link:hover::after { transform: scaleX(1); }
.site-nav__link[aria-current="page"] { color: var(--c-cyan); font-weight: 700; }
.site-nav__link[aria-current="page"]::after { transform: scaleX(1); background: var(--c-orange); }

.site-header__actions { display: flex; align-items: center; gap: 8px; justify-self: end; }

.nav-toggle {
  display: none;
  align-items: center;
  gap: 9px;
  padding: 8px 12px;
  border: 1px solid rgba(25, 227, 209, .5);
  border-radius: 2px;
  color: var(--c-white);
  font-size: .8rem;
  font-weight: 700;
  letter-spacing: .12em;
}
.nav-toggle__bar {
  display: block;
  width: 18px;
  height: 2px;
  background: var(--c-cyan);
  box-shadow: 0 -6px 0 var(--c-cyan), 0 6px 0 var(--c-cyan);
}
.nav-toggle__label { line-height: 1; }
.nav-toggle[aria-expanded="true"] { background: rgba(25, 227, 209, .16); border-color: var(--c-cyan); }

.site-header__ruler {
  height: 6px;
  pointer-events: none;
  opacity: .75;
  background-image: repeating-linear-gradient(90deg, rgba(247, 250, 248, .22) 0 1px, transparent 1px 24px);
}

.scroll-progress {
  position: absolute;
  left: 0; right: 0; bottom: 0;
  height: 3px;
  background: rgba(227, 233, 230, .14);
}
.scroll-progress__fill {
  display: block;
  width: 100%;
  height: 100%;
  transform: scaleX(0);
  transform-origin: left center;
  background: linear-gradient(90deg, var(--c-grass), var(--c-cyan) 68%, var(--c-orange));
  transition: transform .12s linear;
}

/* 18. Footer — 深空蓝收束
   ========================================================================== */
.site-footer {
  position: relative;
  background: var(--c-ink);
  color: var(--on-dark);
}
.site-footer__grid {
  max-width: var(--container);
  margin: 0 auto;
  padding: clamp(40px, 6vw, 76px) var(--gutter) clamp(24px, 3vw, 44px);
  display: grid;
  grid-template-columns: minmax(0, 1.5fr) repeat(4, minmax(0, 1fr));
  gap: clamp(22px, 3vw, 40px);
}
.site-footer__brand { min-width: 0; }
.site-footer__pitch { margin-top: 16px; max-width: 34ch; font-size: .95rem; line-height: 1.85; color: var(--on-dark); }
.site-footer__meta {
  margin-top: 18px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  font-size: 12px;
  letter-spacing: .05em;
  color: rgba(247, 250, 248, .52);
}
.site-footer__meta li { position: relative; padding-left: 14px; }
.site-footer__meta li::before {
  content: "";
  position: absolute;
  left: 0; top: .68em;
  width: 6px; height: 6px;
  background: var(--c-cyan);
}

.footer-col { min-width: 0; }
.footer-col__title {
  padding-bottom: 10px;
  border-bottom: 1px solid var(--line-dark);
  font-size: .82rem;
  font-weight: 900;
  letter-spacing: .16em;
  color: var(--c-white);
}
.footer-col__list { margin-top: 14px; display: flex; flex-direction: column; gap: 9px; font-size: .9rem; }
.footer-col__list a { color: var(--on-dark); transition: color .18s var(--ease); }
.footer-col__list a:hover { color: var(--c-cyan); }
.footer-col__list a[aria-current="page"] { color: var(--c-cyan); font-weight: 700; }

.site-footer__bar {
  max-width: var(--container);
  margin: 0 auto;
  padding: 18px var(--gutter) 22px;
  border-top: 1px solid var(--line-dark);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 8px 20px;
  font-size: 12px;
  letter-spacing: .05em;
  color: rgba(247, 250, 248, .52);
}
.site-footer__legal { color: var(--on-dark); }
.site-footer__contact { flex: 1 1 340px; text-align: center; }
.site-footer__copy { margin-left: auto; }

.site-footer__edge {
  height: 4px;
  background:
    repeating-linear-gradient(90deg, rgba(247, 250, 248, .18) 0 1px, transparent 1px 32px),
    linear-gradient(90deg, var(--c-grass), var(--c-grass-deep) 62%, var(--c-orange));
}

/* 19. Responsive
   ========================================================================== */
@media (max-width: 1180px) {
  .brand__icp { display: none; }
  .btn--quiet { display: none; }
  .site-nav__list { gap: 12px; }
}

@media (max-width: 1024px) {
  .grid--12 { grid-template-columns: repeat(6, minmax(0, 1fr)); }
  .col-4 { grid-column: span 3; }
  .col-5, .col-7 { grid-column: span 6; }
  .col-8 { grid-column: span 6; }
  .site-footer__grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .site-footer__brand { grid-column: span 3; }
}

@media (max-width: 900px) {
  .site-header__frame {
    grid-template-columns: minmax(0, 1fr) auto;
    min-height: 62px;
    gap: 10px;
  }
  .site-header__frame::before,
  .site-header__frame::after { width: 8px; }
  .site-nav {
    display: none;
    position: absolute;
    left: 0; right: 0; top: 100%;
    padding: 12px var(--gutter) 18px;
    background: rgba(11, 27, 43, .98);
    border-top: 1px solid rgba(25, 227, 209, .38);
    border-bottom: 1px solid var(--line-dark);
    box-shadow: 0 26px 44px -30px rgba(0, 0, 0, .9);
    -webkit-backdrop-filter: blur(14px);
    backdrop-filter: blur(14px);
  }
  .site-nav[data-open] { display: block; animation: nav-in .22s var(--ease); }
  @keyframes nav-in { from { opacity: 0; transform: translateY(-8px); } to { opacity: 1; transform: none; } }
  .site-nav__list { flex-direction: column; align-items: stretch; gap: 0; }
  .site-nav__item { border-bottom: 1px dashed rgba(227, 233, 230, .16); }
  .site-nav__item:last-child { border-bottom: 0; }
  .site-nav__link { padding: 13px 4px; font-size: .98rem; }
  .site-nav__link::after { display: none; }
  .site-nav__link[aria-current="page"] { padding-left: 12px; border-left: 3px solid var(--c-orange); }
  .nav-toggle { display: inline-flex; }
  .media--hero { aspect-ratio: 16 / 9; }
  .chapter-index { position: static; }
}

@media (max-width: 760px) {
  .btn--ghost { display: none; }
  .grid--2, .grid--3 { grid-template-columns: minmax(0, 1fr); }
  .grid--12 { grid-template-columns: minmax(0, 1fr); }
  .col-4, .col-5, .col-6, .col-7, .col-8, .col-12 { grid-column: span 1; }
  .site-footer__grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .site-footer__brand { grid-column: span 2; }
  .site-footer__bar { flex-direction: column; align-items: flex-start; }
  .site-footer__contact { text-align: left; }
  .site-footer__copy { margin-left: 0; }
}

@media (max-width: 560px) {
  .brand__line { display: none; }
  .brand__mark { width: 32px; height: 32px; font-size: .72rem; }
  .site-header__actions { gap: 6px; }
  .btn { padding: 8px 12px; font-size: .8rem; }
  .index-list__item { grid-template-columns: 44px minmax(0, 1fr); }
  .index-list__meta { grid-column: 2; }
}

/* 20. Reduced motion
   ========================================================================== */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
    scroll-behavior: auto !important;
  }
  html.js [data-reveal] { opacity: 1; transform: none; }
  .card:hover { transform: none; }
  .scroll-progress__fill { transition: none; }
}