/* ==========================================================================
   B体育主站 · 共享样式表 /assets/site.css
   夜光竞技场 · 战术板粗野主义
   ========================================================================== */

/* ---------- 1. Reset ---------- */
*,
*::before,
*::after { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }

body, h1, h2, h3, h4, h5, h6, p, ul, ol, li, dl, dd, figure, blockquote, fieldset {
  margin: 0;
}

ul, ol { padding: 0; list-style: none; }

img, svg, video { display: block; max-width: 100%; }

button, input, select, textarea { font: inherit; color: inherit; background: none; border: 0; }

a { color: inherit; text-decoration: none; }

table { border-collapse: collapse; width: 100%; }

/* ---------- 2. 设计令牌 ---------- */
:root {
  /* 色彩体系 */
  --c-deep:   #0A1F1A;   /* 深墨绿底座 55% */
  --c-panel:  #111614;   /* 碳黑面板 20% */
  --c-lime:   #C6F24E;   /* 荧光青柠 —— 仅动作与确认 */
  --c-amber:  #FF9E2C;   /* 熔金橙 —— 直播热区与重点场次 */
  --c-bone:   #F4F1E8;   /* 战术板米白 —— 宽松阅读区 */
  --c-stone:  #6E7C74;   /* 岩灰 —— 边框与分隔 */
  --c-moss:   #9FB4A8;   /* 苔绿 —— 次级文字 */
  --c-steel:  #2F7A72;   /* 冷钢青 —— 数据与进度 */
  --c-alert:  #E8563C;   /* 警示赤 —— 版本过期与中断 */
  --c-white:  #EDF3EE;   /* 高亮白 —— 深底正文 */
  --c-ink:    #16211D;   /* 米白区正文 */

  --c-line-dark: #223029;
  --c-line-soft: rgba(110, 124, 116, .28);

  /* 字体 */
  --font-display: "Arial Narrow", "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-body: system-ui, -apple-system, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  --font-serif: Georgia, "Songti SC", "SimSun", serif;

  /* 尺度 */
  --wrap: 1240px;
  --header-h: 76px;
  --border-w: 3px;
  --shadow-hard: 6px 6px 0 var(--c-line-dark);
  --shadow-hard-steel: 5px 5px 0 var(--c-steel);

  --sp-1: 8px;
  --sp-2: 16px;
  --sp-3: 24px;
  --sp-4: 32px;
  --sp-5: 48px;
  --sp-6: 64px;
  --sp-7: 96px;

  /* 动效 */
  --dur-fast: 160ms;
  --dur-mid: 220ms;
  --ease-mech: cubic-bezier(.2, .8, .3, 1);
}

/* ---------- 3. 基础与中文排版 ---------- */
html { background: var(--c-deep); }

body {
  min-height: 100vh;
  background: var(--c-deep);
  color: var(--c-white);
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.75;
  letter-spacing: .01em;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* 场馆栅格底纹 */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(110, 124, 116, .06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(110, 124, 116, .06) 1px, transparent 1px);
  background-size: 88px 88px;
}

body > * { position: relative; z-index: 1; }

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 800;
  letter-spacing: .04em;
  line-height: 1.16;
  text-wrap: balance;
}

h1 { font-size: clamp(2.4rem, 6vw, 4.6rem); }
h2 { font-size: clamp(1.7rem, 3.4vw, 2.6rem); }
h3 { font-size: clamp(1.2rem, 2vw, 1.5rem); }

p { text-wrap: pretty; }

strong { font-weight: 700; color: var(--c-white); }

::selection { background: var(--c-lime); color: var(--c-deep); }

[id] { scroll-margin-top: calc(var(--header-h) + 28px); }

/* ---------- 4. 布局辅助 ---------- */
.wrap {
  width: min(100% - 40px, var(--wrap));
  margin-inline: auto;
}

.wrap--narrow {
  width: min(100% - 40px, 880px);
  margin-inline: auto;
}

.section { padding: clamp(48px, 7vw, 96px) 0; }

.section--tight { padding: clamp(32px, 4vw, 56px) 0; }

.section--bone {
  background: var(--c-bone);
  color: var(--c-ink);
  border-block: var(--border-w) solid var(--c-deep);
}

.section--bone strong { color: #0A1F1A; }
.section--bone .annotation { color: #55645C; }

.grid { display: grid; gap: var(--sp-3); }
.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

.grid--split {
  grid-template-columns: minmax(0, 300px) minmax(0, 1fr);
  gap: var(--sp-5);
  align-items: start;
}

.stack { display: grid; gap: var(--sp-2); align-content: start; }
.stack--loose { gap: var(--sp-4); }

.cluster {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--sp-1) var(--sp-2);
}

/* ---------- 5. 文字层级 ---------- */
.display-xxl {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(2.8rem, 9vw, 7rem);
  line-height: .96;
  letter-spacing: .04em;
  text-transform: uppercase;
}

.display-xl {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(2rem, 5vw, 3.4rem);
  line-height: 1.06;
  letter-spacing: .04em;
}

.display-lg {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(1.5rem, 3vw, 2.2rem);
  letter-spacing: .05em;
  line-height: 1.14;
}

.h3 {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.2rem;
  letter-spacing: .06em;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 12.5px;
  font-weight: 600;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--c-amber);
}

.eyebrow::before {
  content: "";
  width: 18px;
  height: 3px;
  background: currentColor;
  flex: none;
}

.mono {
  font-family: var(--font-mono);
  font-weight: 600;
  letter-spacing: .03em;
  font-variant-numeric: tabular-nums;
}

.lead {
  font-size: clamp(1.02rem, 1.6vw, 1.2rem);
  line-height: 1.8;
  color: var(--c-white);
}

.section--bone .lead { color: #2A3730; }

.annotation {
  font-size: 13.5px;
  line-height: 1.72;
  letter-spacing: .02em;
  color: var(--c-moss);
}

.editorial {
  font-family: var(--font-serif);
  font-size: clamp(1.1rem, 1.8vw, 1.32rem);
  line-height: 1.85;
  letter-spacing: .01em;
}

.rule {
  height: var(--border-w);
  background: var(--c-stone);
  border: 0;
  margin: var(--sp-4) 0;
}

.text-amber { color: var(--c-amber); }
.text-moss { color: var(--c-moss); }
.text-alert { color: var(--c-alert); }

/* ---------- 6. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 12px 22px;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 15px;
  letter-spacing: .08em;
  line-height: 1.2;
  border: var(--border-w) solid transparent;
  cursor: pointer;
  white-space: nowrap;
  transition: transform var(--dur-fast) var(--ease-mech),
              box-shadow var(--dur-fast) var(--ease-mech),
              background-color var(--dur-fast) linear,
              color var(--dur-fast) linear,
              border-color var(--dur-fast) linear;
}

.btn-lime {
  background: var(--c-lime);
  color: var(--c-deep);
  box-shadow: var(--shadow-hard-steel);
}

.btn-lime:hover {
  transform: translate(-2px, -2px);
  box-shadow: 7px 7px 0 var(--c-steel);
}

.btn-lime:active {
  transform: translate(2px, 2px);
  box-shadow: 2px 2px 0 var(--c-steel);
}

.btn-amber {
  background: var(--c-amber);
  color: #21160A;
  box-shadow: 5px 5px 0 #5B3A12;
}

.btn-amber:hover { transform: translate(-2px, -2px); box-shadow: 7px 7px 0 #5B3A12; }
.btn-amber:active { transform: translate(2px, 2px); box-shadow: 2px 2px 0 #5B3A12; }

.btn-ghost {
  background: transparent;
  color: var(--c-white);
  border-color: var(--c-stone);
}

.btn-ghost:hover {
  border-color: var(--c-lime);
  color: var(--c-lime);
  transform: translate(-2px, -2px);
  box-shadow: 5px 5px 0 var(--c-line-dark);
}

.btn-bone {
  background: var(--c-deep);
  color: var(--c-bone);
  box-shadow: 5px 5px 0 var(--c-stone);
}

.btn-bone:hover { transform: translate(-2px, -2px); box-shadow: 7px 7px 0 var(--c-stone); }

.btn--block { width: 100%; }

/* ---------- 7. 标签 / 徽标 / 筛选片 ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 10px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  font-weight: 600;
  letter-spacing: .08em;
  border: 2px solid var(--c-stone);
  color: var(--c-moss);
  background: transparent;
  white-space: nowrap;
}

.tag--lime { border-color: var(--c-lime); color: var(--c-lime); }
.tag--amber { border-color: var(--c-amber); color: var(--c-amber); }
.tag--alert { border-color: var(--c-alert); color: var(--c-alert); }

.section--bone .tag { border-color: #9AA69E; color: #4E5B54; }

.chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: .05em;
  color: var(--c-moss);
  border: var(--border-w) solid var(--c-stone);
  background: var(--c-panel);
  cursor: pointer;
  transition: color var(--dur-fast) linear,
              border-color var(--dur-fast) linear,
              background-color var(--dur-fast) linear,
              transform var(--dur-fast) var(--ease-mech);
}

.chip:hover { color: var(--c-white); border-color: var(--c-moss); transform: translateY(-2px); }

.chip[aria-pressed="true"] {
  background: var(--c-lime);
  border-color: var(--c-lime);
  color: var(--c-deep);
}

.chip--amber[aria-pressed="true"] {
  background: var(--c-amber);
  border-color: var(--c-amber);
  color: #21160A;
}

/* ---------- 8. 面板 / 卡片 / 折叠 / 数据 ---------- */
.panel {
  background: var(--c-panel);
  border: var(--border-w) solid var(--c-stone);
  box-shadow: var(--shadow-hard);
  padding: var(--sp-3);
}

.panel--cut { clip-path: polygon(0 0, 100% 0, 100% calc(100% - 26px), calc(100% - 26px) 100%, 0 100%); }

.panel--flat { box-shadow: none; }

.panel--bone {
  background: var(--c-bone);
  color: var(--c-ink);
  border-color: var(--c-deep);
  box-shadow: 6px 6px 0 var(--c-stone);
}

.card {
  background: var(--c-panel);
  border: var(--border-w) solid var(--c-line-dark);
  border-left: var(--border-w) solid var(--c-steel);
  padding: var(--sp-3);
  transition: transform var(--dur-fast) var(--ease-mech),
              border-left-color var(--dur-fast) linear,
              box-shadow var(--dur-fast) linear;
}

.card:hover {
  transform: translate(-3px, -3px);
  border-left-color: var(--c-amber);
  box-shadow: 6px 6px 0 var(--c-line-dark);
}

.card-title {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.1rem;
  letter-spacing: .05em;
  margin-bottom: var(--sp-1);
}

.stat {
  border: var(--border-w) solid var(--c-stone);
  padding: var(--sp-2) var(--sp-3);
  background: var(--c-panel);
}

.stat-value {
  display: block;
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  letter-spacing: .02em;
  color: var(--c-lime);
  line-height: 1.1;
}

.stat-label {
  display: block;
  margin-top: 6px;
  font-size: 12.5px;
  letter-spacing: .1em;
  color: var(--c-moss);
  font-family: var(--font-mono);
}

.fold {
  border: var(--border-w) solid var(--c-stone);
  background: var(--c-panel);
  margin-bottom: var(--sp-2);
}

.fold > summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-2);
  padding: 16px 20px;
  cursor: pointer;
  list-style: none;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1rem;
  letter-spacing: .05em;
}

.fold > summary::-webkit-details-marker { display: none; }

.fold > summary::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 20px;
  line-height: 1;
  color: var(--c-lime);
  flex: none;
}

.fold[open] > summary {
  background: #0D1A16;
  border-bottom: var(--border-w) solid var(--c-stone);
}

.fold[open] > summary::after { content: "\2212"; color: var(--c-amber); }

.fold-body {
  padding: 18px 20px 22px;
  font-size: 15.5px;
  line-height: 1.78;
  color: var(--c-moss);
}

.section--bone .fold { background: #FFFFFF; border-color: #C9CFC9; }
.section--bone .fold-body { color: #4E5B54; }

.table {
  width: 100%;
  font-size: 15px;
  border: var(--border-w) solid var(--c-stone);
}

.table th,
.table td {
  padding: 12px 14px;
  text-align: left;
  border-bottom: 1px solid var(--c-line-dark);
}

.table th {
  font-family: var(--font-mono);
  font-size: 12.5px;
  font-weight: 600;
  letter-spacing: .08em;
  color: var(--c-moss);
  background: #0D1A16;
}

.table td.numeric { font-family: var(--font-mono); font-variant-numeric: tabular-nums; }

/* ---------- 9. 时间轴 ---------- */
.timeline {
  position: relative;
  padding-left: var(--sp-3);
  border-left: var(--border-w) solid var(--c-steel);
}

.timeline-item { position: relative; padding-bottom: var(--sp-4); }

.timeline-item:last-child { padding-bottom: 0; }

.timeline-dot {
  position: absolute;
  left: calc(-1 * var(--sp-3) - 9px);
  top: 6px;
  width: 15px;
  height: 15px;
  background: var(--c-deep);
  border: var(--border-w) solid var(--c-steel);
}

.timeline-item[data-hot] .timeline-dot {
  border-color: var(--c-amber);
  background: var(--c-amber);
}

/* ---------- 10. 章节目录 ---------- */
.toc {
  position: sticky;
  top: calc(var(--header-h) + 24px);
  display: grid;
  gap: 2px;
  border-left: var(--border-w) solid var(--c-line-dark);
}

.toc-link {
  display: block;
  padding: 10px 14px;
  font-size: 14.5px;
  letter-spacing: .02em;
  color: var(--c-moss);
  border-left: var(--border-w) solid transparent;
  margin-left: calc(-1 * var(--border-w));
  transition: color var(--dur-fast) linear,
              border-color var(--dur-fast) linear,
              background-color var(--dur-fast) linear;
}

.toc-link:hover { color: var(--c-white); background: #0D1A16; }

.toc-link[data-active] {
  color: var(--c-deep);
  background: var(--c-lime);
  border-left-color: var(--c-lime);
  font-weight: 700;
}

/* ---------- 11. 面包屑 ---------- */
.breadcrumb {
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: .04em;
  color: var(--c-moss);
}

.breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

.breadcrumb li + li::before {
  content: "/";
  margin-right: 8px;
  color: var(--c-stone);
}

.breadcrumb a:hover { color: var(--c-lime); }

.breadcrumb [aria-current="page"] { color: var(--c-white); }

/* ---------- 12. 图片容器 ---------- */
.figure {
  --figure-ratio: 16 / 9;
  position: relative;
  display: block;
  width: 100%;
  background: var(--c-panel);
  border: var(--border-w) solid var(--c-stone);
  overflow: hidden;
}

.figure img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  aspect-ratio: var(--figure-ratio);
}

.figure--wide { --figure-ratio: 21 / 9; }
.figure--tall { --figure-ratio: 3 / 4; }
.figure--square { --figure-ratio: 1 / 1; }

.figure figcaption {
  padding: 10px 14px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--c-moss);
  background: #0C1A16;
  border-top: var(--border-w) solid var(--c-stone);
}

.figure[data-placeholder]::before {
  content: attr(data-placeholder);
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  aspect-ratio: var(--figure-ratio);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--c-moss);
  background-image:
    linear-gradient(135deg,
      rgba(47, 122, 114, .22) 0 25%,
      transparent 25% 50%,
      rgba(47, 122, 114, .22) 50% 75%,
      transparent 75%);
  background-size: 24px 24px;
}

/* ---------- 13. 站点头部 ---------- */
.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  z-index: 300;
  padding: 12px 20px;
  background: var(--c-lime);
  color: var(--c-deep);
  font-family: var(--font-display);
  font-weight: 800;
  letter-spacing: .06em;
}

.skip-link:focus { left: 16px; top: 16px; }

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: linear-gradient(180deg, rgba(6, 18, 15, .92) 0%, rgba(6, 18, 15, .62) 62%, rgba(6, 18, 15, 0) 100%);
  transition: background var(--dur-mid) linear,
              box-shadow var(--dur-mid) linear;
}

.site-header::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  height: var(--border-w);
  width: var(--scroll-progress, 0%);
  background: var(--c-steel);
  transition: width 80ms linear;
}

.site-header.is-pinned {
  background: var(--c-panel);
  box-shadow: 0 14px 34px rgba(0, 0, 0, .5),
              inset 0 calc(-1 * var(--border-w)) 0 var(--c-line-dark);
}

.header-inner {
  width: min(100% - 40px, var(--wrap));
  margin-inline: auto;
  min-height: var(--header-h);
  display: flex;
  align-items: center;
  gap: var(--sp-2);
}

/* 品牌 */
.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  flex: none;
}

.brand-mark {
  width: 40px;
  height: 40px;
  flex: none;
  display: grid;
  place-items: center;
  background: var(--c-lime);
  color: var(--c-deep);
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 20px;
  letter-spacing: .02em;
  clip-path: polygon(0 0, 100% 0, 100% 70%, 78% 100%, 0 100%);
  transition: transform var(--dur-fast) var(--ease-mech);
}

.brand:hover .brand-mark { transform: translateY(-2px); }

.brand-text { display: flex; flex-direction: column; gap: 3px; line-height: 1.05; }

.brand-name {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 18px;
  letter-spacing: .08em;
  color: var(--c-white);
}

.brand-sub { display: flex; align-items: center; gap: 10px; }

.brand-badge {
  font-family: var(--font-mono);
  font-size: 10.5px;
  font-weight: 600;
  letter-spacing: .1em;
  padding: 1px 6px;
  background: var(--c-moss);
  color: var(--c-deep);
}

.header-meta {
  display: none;
  font-family: var(--font-mono);
  font-size: 11.5px;
  font-weight: 600;
  letter-spacing: .05em;
  color: var(--c-moss);
  white-space: nowrap;
}

.site-header.is-pinned .header-meta { display: inline-block; }

/* 桌面导航 */
.primary-nav { margin-left: var(--sp-4); }

.nav-list { display: flex; align-items: center; gap: 2px; }

.nav-list a {
  display: block;
  padding: 10px 13px;
  font-size: 15px;
  font-weight: 600;
  letter-spacing: .03em;
  color: var(--c-moss);
  transition: color var(--dur-fast) linear, background-color var(--dur-fast) linear;
}

.nav-list a:hover { color: var(--c-white); }

.nav-list a[aria-current="page"] {
  background: var(--c-lime);
  color: var(--c-deep);
  clip-path: polygon(6px 0, 100% 0, 100% calc(100% - 6px), calc(100% - 6px) 100%, 0 100%, 0 6px);
}

.nav-drawer-foot { display: none; }

/* 头部 CTA 与汉堡按钮 */
.header-cta { margin-left: auto; padding: 11px 18px; font-size: 14px; }

.nav-toggle {
  display: none;
  width: 50px;
  height: 46px;
  flex: none;
  padding: 0;
  border: var(--border-w) solid var(--c-moss);
  background: var(--c-panel);
  cursor: pointer;
  transition: border-color var(--dur-fast) linear;
}

.nav-toggle:hover { border-color: var(--c-lime); }

.nav-toggle-bar {
  display: block;
  width: 22px;
  height: 3px;
  margin: 4px auto;
  background: var(--c-lime);
  transition: transform var(--dur-fast) var(--ease-mech), opacity var(--dur-fast) linear;
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ---------- 14. 站点页脚 ---------- */
.site-footer {
  background: var(--c-panel);
  border-top: var(--border-w) solid var(--c-stone);
  margin-top: clamp(48px, 7vw, 96px);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1.5fr;
  gap: var(--sp-5) var(--sp-4);
  padding: clamp(40px, 5vw, 64px) 0 clamp(28px, 3vw, 44px);
}

.footer-col { min-width: 0; }

.brand--footer .brand-name { font-size: 17px; }

.footer-tag {
  margin-top: var(--sp-2);
  font-size: 14.5px;
  letter-spacing: .03em;
  color: var(--c-white);
}

.footer-tag--dim { color: var(--c-moss); font-size: 13.5px; line-height: 1.7; }

.footer-title {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: var(--sp-2);
  font-family: var(--font-mono);
  font-size: 12.5px;
  font-weight: 600;
  letter-spacing: .16em;
  color: var(--c-moss);
}

.footer-title::before {
  content: "";
  width: 14px;
  height: 3px;
  flex: none;
  background: var(--c-lime);
}

.footer-links li + li { margin-top: 9px; }

.footer-links a {
  position: relative;
  display: inline-block;
  padding-bottom: 2px;
  font-size: 15px;
  color: var(--c-white);
  transition: color var(--dur-fast) linear, transform var(--dur-fast) var(--ease-mech);
}

.footer-links a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 0;
  height: 2px;
  background: currentColor;
  transition: width var(--dur-fast) var(--ease-mech);
}

.footer-links a:hover { color: var(--c-lime); transform: translateX(3px); }
.footer-links a:hover::after { width: 100%; }

.footer-contact { display: grid; gap: 10px; }

.footer-contact li {
  display: grid;
  grid-template-columns: 46px minmax(0, 1fr);
  gap: 10px;
  align-items: baseline;
  font-size: 14.5px;
  color: var(--c-white);
}

.footer-contact .label {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: .08em;
  color: var(--c-moss);
}

.footer-contact .value { word-break: break-word; }

.footer-note {
  margin-top: var(--sp-2);
  padding-left: 12px;
  border-left: var(--border-w) solid var(--c-amber);
  font-size: 13px;
  line-height: 1.72;
  color: var(--c-moss);
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 12px;
  padding: 18px 0 30px;
  border-top: 1px solid var(--c-line-dark);
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: .04em;
  color: var(--c-moss);
}

.footer-sep { color: var(--c-stone); }

.footer-bottom-tail { margin-left: auto; }

/* ---------- 15. 返回顶部 ---------- */
.to-top {
  position: fixed;
  right: 20px;
  bottom: 20px;
  z-index: 95;
  width: 50px;
  height: 50px;
  display: grid;
  place-items: center;
  background: var(--c-lime);
  color: var(--c-deep);
  border: var(--border-w) solid var(--c-deep);
  box-shadow: 5px 5px 0 var(--c-steel);
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(14px);
  transition: opacity var(--dur-fast) linear,
              transform var(--dur-fast) var(--ease-mech),
              visibility var(--dur-fast) linear;
}

.to-top[data-visible] {
  opacity: 1;
  visibility: visible;
  transform: none;
}

.to-top:hover { transform: translate(-2px, -2px); box-shadow: 7px 7px 0 var(--c-steel); }

/* ---------- 16. 显现与状态 ---------- */
html.js [data-reveal] {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity var(--dur-mid) var(--ease-mech),
              transform var(--dur-mid) var(--ease-mech);
}

html.js [data-reveal].is-in { opacity: 1; transform: none; }

html.nav-open { overflow: hidden; }

html.nav-open body { overflow: hidden; }

/* ---------- 17. 焦点可见 ---------- */
:focus-visible {
  outline: 3px solid var(--c-amber);
  outline-offset: 3px;
}

a:focus-visible,
button:focus-visible,
summary:focus-visible,
.chip:focus-visible,
.toc-link:focus-visible {
  outline: 3px solid var(--c-amber);
  outline-offset: 3px;
}

/* ---------- 18. 响应式 ---------- */
@media (max-width: 1080px) {
  .nav-list a { padding: 10px 10px; font-size: 14.5px; }
  .primary-nav { margin-left: var(--sp-3); }
  .header-meta { display: none !important; }
  .footer-grid { grid-template-columns: 1.4fr 1fr 1fr; }
  .footer-col--contact { grid-column: 1 / -1; }
}

@media (max-width: 1024px) {
  :root { --header-h: 68px; }

  .nav-toggle { display: block; margin-left: auto; order: 3; }
  .header-cta { display: none; }

  .primary-nav {
    position: fixed;
    inset: 0;
    z-index: 90;
    margin: 0;
    padding: calc(var(--header-h) + 28px) 24px 40px;
    background: var(--c-deep);
    border-right: none;
    overflow-y: auto;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-14px);
    transition: opacity var(--dur-mid) linear,
                transform var(--dur-mid) var(--ease-mech),
                visibility var(--dur-mid) linear;
  }

  .primary-nav[data-open] {
    opacity: 1;
    visibility: visible;
    transform: none;
  }

  .nav-list { flex-direction: column; align-items: stretch; gap: 0; }

  .nav-list a {
    padding: 18px 6px;
    font-family: var(--font-display);
    font-weight: 800;
    font-size: 22px;
    letter-spacing: .05em;
    color: var(--c-white);
    border-bottom: var(--border-w) solid var(--c-line-dark);
  }

  .nav-list a[aria-current="page"] {
    background: transparent;
    color: var(--c-lime);
    clip-path: none;
    padding-left: 16px;
  }

  .nav-drawer-foot {
    display: grid;
    gap: var(--sp-2);
    margin-top: var(--sp-5);
  }

  .nav-cta { width: 100%; }

  .nav-drawer-note {
    font-family: var(--font-mono);
    font-size: 12px;
    letter-spacing: .05em;
    color: var(--c-moss);
  }

  .grid--split { grid-template-columns: minmax(0, 1fr); gap: var(--sp-4); }
  .toc { position: static; }
  .grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 820px) {
  .grid--3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-col--brand { grid-column: 1 / -1; }
}

@media (max-width: 640px) {
  body { font-size: 16px; }
  .wrap, .wrap--narrow, .header-inner { width: min(100% - 32px, var(--wrap)); }
  .grid--2, .grid--3, .grid--4 { grid-template-columns: minmax(0, 1fr); }
  .footer-grid { grid-template-columns: minmax(0, 1fr); gap: var(--sp-4); }
  .footer-col--contact { grid-column: auto; }
  .brand-name { font-size: 16px; }
  .brand-mark { width: 36px; height: 36px; font-size: 18px; }
  .to-top { right: 14px; bottom: 14px; width: 46px; height: 46px; }
  .panel { padding: var(--sp-2); }
  .footer-bottom-tail { margin-left: 0; width: 100%; }
  .figure[data-placeholder]::before { font-size: 11px; letter-spacing: .1em; }
}

/* ---------- 19. 动效偏好 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *,
  *::before,
  *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
    scroll-behavior: auto !important;
  }

  html.js [data-reveal] { opacity: 1; transform: none; }
}