/* ============================================================
   完美体育主站 · 共享外壳样式 (assets/site.css)
   夜场灯光 / 精密网格 / 直角记分板
   ============================================================ */

/* ---------- reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body, h1, h2, h3, h4, p, ul, ol, figure, blockquote, fieldset { margin: 0; }
ul, ol { padding: 0; list-style: none; }
img, svg, video { display: block; max-width: 100%; height: auto; }
button, input, select, textarea { font: inherit; color: inherit; }
button { cursor: pointer; }
table { border-collapse: collapse; }

/* ---------- tokens ---------- */
:root {
  --ink: #0A100E;
  --forest: #0E2B23;
  --pitch: #173D31;
  --char: #12171A;
  --cyan: #2FF3D6;
  --orange: #FF6A2B;
  --paper: #F4F1E9;
  --mist: #9AA8A3;
  --line: #24312D;
  --warn: #F5C542;

  --cyan-a08: rgba(47, 243, 214, 0.08);
  --cyan-a16: rgba(47, 243, 214, 0.16);
  --cyan-a40: rgba(47, 243, 214, 0.40);
  --orange-a12: rgba(255, 106, 43, 0.12);
  --orange-a45: rgba(255, 106, 43, 0.45);

  --font-display: "Barlow Condensed", "Oswald", "Source Han Sans SC", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-body: "Inter", "Source Han Sans SC", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, "SFMono-Regular", Consolas, "Liberation Mono", monospace;

  --header-h: 88px;
  --header-h-compact: 60px;
  --maxw: 1280px;
  --gutter: clamp(16px, 4vw, 40px);
  --space: 8px;
}

/* ---------- base ---------- */
body {
  background-color: var(--ink);
  background-image:
    linear-gradient(to right, rgba(36, 49, 45, 0.55) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(36, 49, 45, 0.55) 1px, transparent 1px);
  background-size: 96px 96px;
  color: var(--paper);
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.75;
  font-weight: 400;
  letter-spacing: 0.01em;
}

#main-content { display: block; scroll-margin-top: calc(var(--header-h) + 16px); }

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 800;
  line-height: 1.05;
  letter-spacing: 0.01em;
  color: var(--paper);
}

a { color: var(--cyan); text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { text-decoration-thickness: 2px; }

:where(a, button, summary, [tabindex]):focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 3px;
}

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

/* ---------- typography utilities ---------- */
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--cyan);
}
.eyebrow::before { content: ""; width: 24px; height: 1px; background: var(--cyan); }

.display-xl { font-size: clamp(42px, 7vw, 88px); line-height: 1.02; }
.display-l { font-size: clamp(32px, 4.6vw, 56px); }
.display-m { font-size: clamp(24px, 3vw, 40px); }

.lede {
  font-size: clamp(16px, 1.6vw, 20px);
  line-height: 1.7;
  color: rgba(244, 241, 233, 0.84);
  max-width: 44ch;
}

.prose { max-width: 34em; }
.prose p, .prose ul, .prose ol { margin-top: 1em; }
.prose p:first-child, .prose ul:first-child, .prose ol:first-child { margin-top: 0; }
.prose p { color: rgba(244, 241, 233, 0.86); }
.prose ul { list-style: disc; padding-left: 1.2em; }
.prose ol { list-style: decimal; padding-left: 1.4em; }
.prose li + li { margin-top: 0.4em; }
.prose h2, .prose h3 { margin-top: 1.8em; }
.prose strong { color: var(--paper); }

/* ---------- layout ---------- */
.shell {
  width: 100%;
  max-width: var(--maxw);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section { padding-block: clamp(56px, 7vw, 112px); }
.section--tight { padding-block: clamp(36px, 4vw, 64px); }

.band { background-color: var(--forest); }
.band--forest { background-color: var(--forest); }
.band--char { background-color: var(--char); }
.band--paper { background-color: var(--paper); color: var(--char); }
.band--paper h1, .band--paper h2, .band--paper h3, .band--paper h4 { color: var(--char); }
.band--paper .lede, .band--paper .prose p { color: rgba(18, 23, 26, 0.82); }
.band--paper a { color: #0B6B5C; }
.band--paper .eyebrow { color: #0B6B5C; }
.band--paper .eyebrow::before { background: #0B6B5C; }

.grid-12 {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: clamp(16px, 2vw, 32px);
}
.col-2 { grid-column: span 2; }
.col-3 { grid-column: span 3; }
.col-4 { grid-column: span 4; }
.col-6 { grid-column: span 6; }
.col-8 { grid-column: span 8; }
.col-12 { grid-column: span 12; }

/* 叙事章节三列：索引 / 主叙事 / 浮动信息 */
.chapter {
  display: grid;
  grid-template-columns: 84px minmax(0, 1fr) 300px;
  gap: clamp(16px, 2.4vw, 40px);
  align-items: start;
}
.chapter-index {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--cyan);
  border-top: 1px solid var(--line);
  padding-top: 10px;
}
.chapter-main { min-width: 0; }
.chapter-aside {
  border-top: 1px solid var(--line);
  padding-top: 14px;
  display: grid;
  gap: 16px;
}

/* ---------- breadcrumbs ---------- */
.breadcrumbs {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--mist);
}
.breadcrumbs-list { display: flex; flex-wrap: wrap; gap: 8px; }
.breadcrumbs-item { display: inline-flex; align-items: center; gap: 8px; }
.breadcrumbs-item::after { content: "/"; color: var(--line); }
.breadcrumbs-item:last-child::after { content: none; }
.breadcrumbs a { color: inherit; text-decoration: none; }
.breadcrumbs a:hover { color: var(--cyan); }

/* ---------- buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 42px;
  padding: 0 18px;
  border: 1px solid transparent;
  border-radius: 0;
  font-family: var(--font-body);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-decoration: none;
  white-space: nowrap;
  transition: background-color 140ms ease-out, border-color 140ms ease-out, color 140ms ease-out;
}
.btn-primary { background: var(--orange); color: var(--char); border-color: var(--orange); }
.btn-primary:hover { background: #FF824F; border-color: #FF824F; }
.btn-ghost { background: transparent; color: var(--paper); border-color: var(--line); }
.btn-ghost:hover { color: var(--cyan); border-color: var(--cyan); background: var(--cyan-a08); }

/* ---------- skip link ---------- */
.skip-link {
  position: fixed;
  left: 16px;
  top: -120px;
  z-index: 300;
  padding: 12px 18px;
  background: var(--cyan);
  color: var(--ink);
  font-weight: 700;
  font-size: 14px;
  text-decoration: none;
  transition: top 140ms ease-out;
}
.skip-link:focus { top: 12px; }

/* ---------- header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-h);
  background-color: rgba(10, 16, 14, 0.30);
  border-bottom: 1px solid transparent;
  transition: background-color 200ms ease-out, border-color 200ms ease-out, height 160ms ease-out;
}
.site-header[data-scrolled="true"] {
  background-color: var(--forest);
  border-bottom-color: var(--line);
  height: var(--header-h-compact);
}

.header-inner {
  position: relative;
  z-index: 95;
  display: flex;
  align-items: center;
  gap: clamp(12px, 2vw, 28px);
  height: 100%;
  max-width: var(--maxw);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

/* 品牌 */
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--paper);
  flex: 0 0 auto;
}
.brand-dot {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--cyan);
  box-shadow: 0 0 0 4px var(--cyan-a16);
  flex: 0 0 auto;
}
.brand-text { display: flex; flex-direction: column; gap: 3px; line-height: 1; }
.brand-name {
  font-family: var(--font-display);
  font-size: 22px;
  font-weight: 800;
  letter-spacing: 0.02em;
}
.brand-sub {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.18em;
  color: var(--mist);
}

/* 导航 */
.site-nav { margin-inline: auto; }
.nav-list { display: flex; align-items: center; gap: clamp(8px, 1.6vw, 26px); }
.nav-item { flex: 0 0 auto; }
.nav-link {
  position: relative;
  display: inline-block;
  padding: 9px 2px;
  font-size: 14px;
  letter-spacing: 0.06em;
  color: rgba(244, 241, 233, 0.78);
  text-decoration: none;
  transition: color 140ms ease-out;
}
.nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 2px;
  background: var(--cyan);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 140ms ease-out;
}
.nav-link:hover { color: var(--paper); }
.nav-link:hover::after { transform: scaleX(1); }
.nav-link[aria-current="page"] { color: var(--cyan); }
.nav-link[aria-current="page"]::after { transform: scaleX(1); }

.drawer-quick { display: none; }

.header-actions { display: flex; align-items: center; gap: 8px; flex: 0 0 auto; }

/* 移动开关 */
.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  min-height: 40px;
  padding: 8px 10px;
  background: transparent;
  border: 1px solid var(--line);
  border-radius: 0;
  color: var(--paper);
  font-size: 12px;
  letter-spacing: 0.1em;
  flex: 0 0 auto;
}
.nav-toggle:hover { border-color: var(--cyan); color: var(--cyan); }
.nav-toggle-bars { display: inline-grid; gap: 3px; width: 16px; }
.nav-toggle-bars > span {
  display: block;
  height: 2px;
  background: currentColor;
  transition: transform 140ms ease-out, opacity 140ms ease-out;
}
.site-header[data-open="true"] .nav-toggle-bars > span:nth-child(1) { transform: translateY(5px) rotate(45deg); }
.site-header[data-open="true"] .nav-toggle-bars > span:nth-child(2) { opacity: 0; }
.site-header[data-open="true"] .nav-toggle-bars > span:nth-child(3) { transform: translateY(-5px) rotate(-45deg); }
.nav-toggle-text { font-family: var(--font-mono); }

/* 滚动进度光带 */
.scroll-meter {
  position: absolute;
  left: 0;
  bottom: -1px;
  width: 100%;
  height: 2px;
  background: linear-gradient(90deg, var(--cyan), var(--orange));
  transform: scaleX(0);
  transform-origin: left center;
  pointer-events: none;
}

/* ---------- footer ---------- */
.site-footer {
  background-color: var(--ink);
  border-top: 1px solid var(--line);
  color: var(--paper);
}
.footer-inner {
  max-width: var(--maxw);
  margin-inline: auto;
  padding: clamp(48px, 6vw, 80px) var(--gutter) 28px;
  display: grid;
  gap: clamp(32px, 4vw, 52px);
}
.footer-mast {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: 20px 48px;
  padding-bottom: 28px;
  border-bottom: 1px solid var(--line);
}
.footer-brand { display: flex; flex-direction: column; gap: 8px; }
.footer-brand-name {
  display: flex;
  align-items: baseline;
  gap: 8px;
  font-family: var(--font-display);
  font-size: 26px;
  font-weight: 800;
  letter-spacing: 0.02em;
  line-height: 1;
}
.footer-brand-mark {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 400;
  letter-spacing: 0.2em;
  color: var(--cyan);
}
.footer-brand-sub {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.2em;
  color: var(--mist);
}
.footer-tagline {
  max-width: 44ch;
  font-size: 15px;
  line-height: 1.7;
  color: rgba(244, 241, 233, 0.76);
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 28px clamp(16px, 3vw, 40px);
}
.footer-col { min-width: 0; }
.footer-col-title {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--cyan);
  margin-bottom: 14px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--line);
}
.footer-links { display: grid; gap: 10px; }
.footer-links a {
  font-size: 14px;
  color: rgba(244, 241, 233, 0.80);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 140ms ease-out, border-color 140ms ease-out;
}
.footer-links a:hover { color: var(--cyan); border-bottom-color: var(--cyan-a40); }
.footer-links--status li {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  line-height: 1.5;
  color: rgba(244, 241, 233, 0.78);
}

.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--cyan);
  flex: 0 0 auto;
}
.status-dot--orange { background: var(--orange); }
.status-dot--warn { background: var(--warn); }

.footer-contact {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 18px 28px;
  padding-top: 28px;
  border-top: 1px solid var(--line);
}
.footer-contact-item { display: grid; gap: 6px; }
.footer-contact-label {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--mist);
}
.footer-contact-value {
  font-family: var(--font-mono);
  font-size: 14px;
  line-height: 1.5;
  color: var(--paper);
  word-break: break-word;
}

.footer-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 28px;
  padding-top: 20px;
  border-top: 1px solid var(--line);
  font-size: 13px;
  color: var(--mist);
}
.footer-legal { display: flex; flex-wrap: wrap; gap: 8px 20px; }
.footer-copy { font-family: var(--font-mono); font-size: 12px; letter-spacing: 0.08em; }

/* ---------- card ---------- */
.card {
  background: var(--forest);
  border: 1px solid var(--line);
  border-radius: 0;
  padding: clamp(18px, 2.2vw, 26px);
  transition: border-color 140ms ease-out, background-color 140ms ease-out;
}
.card:hover { border-color: var(--cyan); background: #113128; }
.card-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 14px;
}
.card-title {
  font-family: var(--font-display);
  font-size: 22px;
  font-weight: 800;
  line-height: 1.15;
}
.card-body { font-size: 15px; line-height: 1.7; color: rgba(244, 241, 233, 0.82); }
.card-meta {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--mist);
}

/* ---------- tag ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 8px;
  border: 1px solid var(--line);
  border-radius: 0;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--mist);
  background: transparent;
}
.tag--cyan { color: var(--cyan); border-color: var(--cyan-a40); background: var(--cyan-a08); }
.tag--orange { color: #FFB08C; border-color: var(--orange-a45); background: var(--orange-a12); }
.tag--warn { color: var(--char); background: var(--warn); border-color: var(--warn); }

/* ---------- stat ---------- */
.stat { border-left: 2px solid var(--cyan); padding-left: 14px; }
.stat-value {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(26px, 3.6vw, 42px);
  font-weight: 600;
  line-height: 1.1;
  letter-spacing: -0.02em;
  font-variant-numeric: tabular-nums;
  color: var(--paper);
}
.stat-label {
  display: block;
  margin-top: 6px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--mist);
}

/* ---------- table ---------- */
.data-table { width: 100%; font-size: 15px; }
.data-table th {
  text-align: left;
  padding: 10px 12px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--cyan);
  border-bottom: 1px solid var(--cyan-a40);
  white-space: nowrap;
}
.data-table td {
  padding: 12px;
  border-bottom: 1px solid var(--line);
  color: rgba(244, 241, 233, 0.86);
  vertical-align: top;
}
.data-table tbody tr { transition: background-color 140ms ease-out; }
.data-table tbody tr:hover td { background: rgba(23, 61, 49, 0.55); color: var(--paper); }
.data-table .num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.01em;
}

/* ---------- details solver ---------- */
.solver {
  border: 1px solid var(--line);
  background: var(--char);
}
.solver + .solver { margin-top: 8px; }
.solver summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding: 14px 16px;
  font-weight: 600;
  font-size: 15px;
  cursor: pointer;
  list-style: none;
  transition: background-color 140ms ease-out, color 140ms ease-out;
}
.solver summary::-webkit-details-marker { display: none; }
.solver summary::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 16px;
  color: var(--cyan);
  flex: 0 0 auto;
}
.solver[open] summary::after { content: "–"; }
.solver summary:hover { background: var(--forest); color: var(--paper); }
.solver-body {
  padding: 0 16px 18px;
  font-size: 15px;
  line-height: 1.7;
  color: rgba(244, 241, 233, 0.82);
  border-top: 1px solid var(--line);
  padding-top: 14px;
}

/* ---------- media frame ---------- */
.media-frame {
  position: relative;
  display: block;
  margin: 0;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 0;
  aspect-ratio: 16 / 9;
  background: linear-gradient(150deg, var(--pitch) 0%, var(--ink) 78%);
}
.media-frame::before {
  content: "";
  position: absolute;
  inset: 0;
  background: repeating-linear-gradient(115deg, rgba(47, 243, 214, 0.07) 0 1px, transparent 1px 14px);
  pointer-events: none;
  z-index: 1;
}
.media-frame img {
  position: relative;
  z-index: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: saturate(0.92) contrast(1.04);
}
.media-frame figcaption {
  position: absolute;
  z-index: 2;
  left: 0;
  bottom: 0;
  padding: 8px 12px;
  background: rgba(10, 16, 14, 0.80);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--paper);
}
.media-frame--wide { aspect-ratio: 21 / 9; }
.media-frame--tall { aspect-ratio: 4 / 5; }

/* ---------- tabs ---------- */
.tabs {
  display: flex;
  flex-wrap: wrap;
  border-bottom: 1px solid var(--line);
}
.tab {
  appearance: none;
  min-height: 44px;
  padding: 10px 14px;
  background: transparent;
  border: 0;
  border-bottom: 2px solid transparent;
  border-radius: 0;
  font-size: 13px;
  letter-spacing: 0.1em;
  color: var(--mist);
  transition: color 140ms ease-out, border-color 140ms ease-out;
}
.tab:hover { color: var(--paper); }
.tab[aria-selected="true"] { color: var(--cyan); border-bottom-color: var(--cyan); }
.tabpanel { padding-top: 18px; }
.tabpanel[hidden] { display: none; }

/* ---------- reveal ---------- */
[data-reveal] {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 260ms ease-out, transform 260ms ease-out;
}
[data-reveal].is-visible { opacity: 1; transform: none; }

/* ---------- responsive : tablet ---------- */
@media (max-width: 1024px) {
  :root { --header-h: 68px; --header-h-compact: 60px; }

  .nav-toggle { display: inline-flex; }
  .header-actions .btn-ghost { display: none; }
  .brand { margin-right: auto; }

  .site-nav {
    position: fixed;
    inset: 0;
    z-index: 90;
    display: none;
    flex-direction: column;
    margin-inline: 0;
    padding: calc(var(--header-h) + 28px) var(--gutter) 48px;
    overflow-y: auto;
    background-color: var(--ink);
    background-image: linear-gradient(to bottom, rgba(14, 43, 35, 0.94) 0%, var(--ink) 42%);
    border-bottom: 1px solid var(--cyan);
  }
  .site-header[data-open="true"] .site-nav { display: flex; }
  .site-header[data-open="true"] .header-inner { background-color: var(--ink); }

  .drawer-quick {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 8px;
    margin-bottom: 28px;
  }
  .drawer-quick-link {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 48px;
    padding: 6px 4px;
    border: 1px solid var(--line);
    background: var(--forest);
    color: var(--cyan);
    font-family: var(--font-mono);
    font-size: 12px;
    letter-spacing: 0.1em;
    text-align: center;
    text-decoration: none;
    transition: border-color 140ms ease-out, background-color 140ms ease-out;
  }
  .drawer-quick-link:hover { border-color: var(--cyan); background: var(--cyan-a08); }

  .nav-list { flex-direction: column; align-items: stretch; gap: 0; counter-reset: navcounter; }
  .nav-item { counter-increment: navcounter; border-bottom: 1px solid var(--line); }
  .nav-link {
    display: flex;
    align-items: center;
    gap: 14px;
    padding: 18px 0;
    font-size: 20px;
    letter-spacing: 0.03em;
    color: var(--paper);
  }
  .nav-link::before {
    content: counter(navcounter, decimal-leading-zero);
    font-family: var(--font-mono);
    font-size: 11px;
    letter-spacing: 0.14em;
    color: var(--mist);
  }
  .nav-link::after {
    content: "↗";
    position: static;
    width: auto;
    height: auto;
    margin-left: auto;
    background: none;
    transform: none;
    color: var(--mist);
    font-size: 14px;
  }
  .nav-link[aria-current="page"] { color: var(--cyan); }
  .nav-link[aria-current="page"]::after { color: var(--cyan); }

  .chapter { grid-template-columns: 64px minmax(0, 1fr); }
  .chapter-aside { grid-column: 1 / -1; }

  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

/* ---------- responsive : small tablet ---------- */
@media (max-width: 900px) {
  .grid-12 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid-12 > * { grid-column: span 2; }
}

/* ---------- responsive : phone ---------- */
@media (max-width: 640px) {
  body { font-size: 16px; line-height: 1.7; }

  .brand-name { font-size: 19px; }
  .brand-sub { display: none; }
  .header-actions .btn { min-height: 36px; padding: 0 12px; font-size: 12px; }
  .nav-toggle { min-height: 36px; padding: 6px 8px; }
  .nav-toggle-text { display: none; }

  .section { padding-block: clamp(44px, 9vw, 64px); }

  .grid-12 { grid-template-columns: minmax(0, 1fr); }
  .grid-12 > * { grid-column: span 1; }

  .chapter { grid-template-columns: minmax(0, 1fr); gap: 14px; }
  .chapter-index { border-top: 0; padding-top: 0; }

  .footer-grid { grid-template-columns: minmax(0, 1fr); }
  .footer-mast { align-items: flex-start; }
  .footer-contact { grid-template-columns: minmax(0, 1fr); }
  .footer-meta { flex-direction: column; align-items: flex-start; }
}

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