/* =========================================================
   KY赛场 · 共享样式表 /assets/site.css
   设计基因：赛场夜灯下的技术面板 · 左侧发光轨道 · 记分牌数字
   ========================================================= */

/* ---------- 01. Reset ---------- */
*,
*::before,
*::after { box-sizing: border-box; }

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

body, h1, h2, h3, h4, h5, h6, p, figure, blockquote, dl, dd, ul, ol { margin: 0; }
ul, ol { padding: 0; list-style: none; }
img, svg, video, canvas { display: block; max-width: 100%; }
img { height: auto; }
a { color: inherit; }
button { font: inherit; color: inherit; background: none; border: 0; }
h1, h2, h3, h4, h5, h6 { font-size: inherit; font-weight: inherit; }
table { border-collapse: collapse; width: 100%; }

/* ---------- 02. 变量 ---------- */
:root {
  --ink-900: #030A12;
  --ink-800: #071426;
  --ink-700: #0D2138;
  --ink-600: #123049;

  --cyan: #37F2D2;
  --cyan-12: rgba(55, 242, 210, .12);
  --cyan-24: rgba(55, 242, 210, .24);
  --cyan-45: rgba(55, 242, 210, .45);

  --orange: #FF7A1A;
  --orange-12: rgba(255, 122, 26, .12);

  --paper: #F2E9DA;
  --paper-light: #FBF6EC;
  --glass: #A9C7D9;
  --muted: #7E9BAC;
  --grid: #2B4A5E;
  --grid-soft: rgba(43, 74, 94, .55);
  --text: #EAF6F5;

  --green: #5BE38A;
  --amber: #F5C451;

  --font-display: "Helvetica Neue", "Arial Narrow", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-body: "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  --font-mono: ui-monospace, "SFMono-Regular", "JetBrains Mono", "Roboto Mono", Menlo, Consolas, monospace;
  --font-serif: "Noto Serif SC", "Songti SC", "Source Han Serif SC", Georgia, "Times New Roman", serif;

  --shell: min(1360px, calc(100% - 48px));
  --radius: 2px;
  --ease: cubic-bezier(.22, .61, .36, 1);
  --dur: .24s;
}

/* ---------- 03. 页面底色与中文排版 ---------- */
body {
  min-height: 100vh;
  background-color: var(--ink-800);
  background-image:
    linear-gradient(to right, rgba(43, 74, 94, .22) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(43, 74, 94, .22) 1px, transparent 1px),
    radial-gradient(1100px 720px at 86% -14%, rgba(55, 242, 210, .10), transparent 64%),
    radial-gradient(900px 620px at 2% 104%, rgba(255, 122, 26, .07), transparent 62%);
  background-size: 72px 72px, 72px 72px, 100% 100%, 100% 100%;
  background-attachment: fixed;
  color: var(--text);
  font-family: var(--font-body);
  font-size: 16px;
  font-weight: 400;
  line-height: 1.7;
  letter-spacing: .01em;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

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

#main-content { display: block; }

:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 3px;
  border-radius: var(--radius);
}
:focus:not(:focus-visible) { outline: none; }

/* ---------- 04. 跳转链接 ---------- */
.skip-link {
  position: absolute;
  left: 16px;
  top: 10px;
  z-index: 999;
  padding: 10px 18px;
  background: var(--cyan);
  color: var(--ink-900);
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: .08em;
  text-decoration: none;
  transform: translateY(-180%);
  transition: transform var(--dur) var(--ease);
}
.skip-link:focus-visible { transform: translateY(0); }

/* ---------- 05. 头部 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 200;
  background: rgba(3, 10, 18, .9);
  -webkit-backdrop-filter: blur(16px) saturate(140%);
  backdrop-filter: blur(16px) saturate(140%);
  border-bottom: 1px solid var(--grid-soft);
}

.site-header::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 3px;
  background: linear-gradient(to bottom, var(--cyan) 0%, rgba(55, 242, 210, 0) 52%, var(--orange) 100%);
  opacity: .9;
  pointer-events: none;
}

.header-inner {
  position: relative;
  width: var(--shell);
  margin-inline: auto;
  min-height: 76px;
  padding-block: 12px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
}

/* 品牌 */
.brand {
  display: flex;
  align-items: center;
  gap: 14px;
  min-width: 0;
}

.brand-mark {
  position: relative;
  flex: none;
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
  border: 1px solid var(--cyan-45);
  background: linear-gradient(155deg, rgba(55, 242, 210, .16), rgba(55, 242, 210, 0) 62%);
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: 600;
  letter-spacing: .1em;
  text-decoration: none;
  transition: border-color var(--dur) var(--ease), box-shadow var(--dur) var(--ease);
}
.brand-mark::after {
  content: "";
  position: absolute;
  right: -1px;
  bottom: -1px;
  width: 11px;
  height: 11px;
  border-right: 2px solid var(--orange);
  border-bottom: 2px solid var(--orange);
}
.brand-mark:hover,
.brand-mark:focus-visible {
  border-color: var(--cyan);
  box-shadow: 0 0 20px rgba(55, 242, 210, .28);
}

.brand-text {
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.brand-name {
  font-family: var(--font-display);
  font-size: 21px;
  font-weight: 800;
  letter-spacing: .05em;
  line-height: 1.2;
  color: var(--text);
  text-decoration: none;
  transition: color var(--dur) var(--ease);
}
.brand-name:hover { color: var(--cyan); }

.brand-tagline {
  margin-top: 3px;
  font-size: 12px;
  line-height: 1.4;
  letter-spacing: .04em;
  color: var(--muted);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.version-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  flex: none;
  padding: 5px 10px;
  border: 1px solid var(--cyan-24);
  background: var(--cyan-12);
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: .12em;
  line-height: 1.5;
  white-space: nowrap;
}

.version-badge-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--green);
  box-shadow: 0 0 9px rgba(91, 227, 138, .75);
  flex: none;
}

/* 右侧 */
.header-end {
  display: flex;
  align-items: center;
  gap: 16px;
  min-width: 0;
}

.nav-cluster {
  display: flex;
  align-items: center;
  gap: 22px;
}

.site-nav { min-width: 0; }

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

.nav-link {
  position: relative;
  display: inline-block;
  padding: 8px 11px;
  font-size: 14px;
  font-weight: 500;
  letter-spacing: .02em;
  color: var(--glass);
  text-decoration: none;
  transition: color var(--dur) var(--ease);
}
.nav-link::after {
  content: "";
  position: absolute;
  left: 11px;
  right: 11px;
  bottom: 3px;
  height: 1px;
  background: var(--cyan);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform var(--dur) var(--ease);
}
.nav-link:hover { color: var(--text); }
.nav-link:hover::after { transform: scaleX(1); }
.nav-link[aria-current="page"] { color: var(--cyan); }
.nav-link[aria-current="page"]::after { transform: scaleX(1); }
.nav-list li[aria-current="page"] > .nav-link { color: var(--cyan); }
.nav-list li[aria-current="page"] > .nav-link::after { transform: scaleX(1); }

.header-actions {
  display: flex;
  align-items: center;
  gap: 14px;
}

.header-utility {
  font-size: 13px;
  color: var(--glass);
  text-decoration: none;
  padding-bottom: 2px;
  border-bottom: 1px dashed rgba(169, 199, 217, .45);
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.header-utility:hover,
.header-utility:focus-visible {
  color: var(--cyan);
  border-color: var(--cyan);
}

/* 移动按钮 */
.nav-toggle {
  display: none;
  align-items: center;
  gap: 9px;
  padding: 9px 12px;
  border: 1px solid var(--cyan-45);
  color: var(--cyan);
  cursor: pointer;
  transition: background var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.nav-toggle:hover { background: var(--cyan-12); border-color: var(--cyan); }

.nav-toggle-icon {
  width: 16px;
  display: grid;
  gap: 5px;
}
.nav-toggle-bar {
  display: block;
  width: 100%;
  height: 1.5px;
  background: currentColor;
  transition: transform var(--dur) var(--ease);
}
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(1) { transform: translateY(3.25px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(2) { transform: translateY(-3.25px) rotate(-45deg); }

.nav-toggle-text {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: .14em;
}

/* 阅读进度 */
.scroll-meter {
  position: absolute;
  left: 0;
  right: 0;
  bottom: -1px;
  height: 2px;
  background: transparent;
  pointer-events: none;
}
.scroll-meter-fill {
  display: block;
  height: 100%;
  width: 0;
  background: linear-gradient(90deg, var(--cyan), var(--orange));
  box-shadow: 0 0 12px rgba(55, 242, 210, .55);
}

/* ---------- 06. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: .55em;
  padding: 12px 20px;
  border: 1px solid transparent;
  border-radius: var(--radius);
  font-family: var(--font-body);
  font-size: 14px;
  font-weight: 700;
  letter-spacing: .03em;
  line-height: 1.4;
  text-decoration: none;
  cursor: pointer;
  transition: background var(--dur) var(--ease), color var(--dur) var(--ease),
              border-color var(--dur) var(--ease), box-shadow var(--dur) var(--ease),
              transform 90ms var(--ease);
}
.btn:active { transform: translateY(1px); }

.btn--primary {
  background: var(--orange);
  color: var(--ink-900);
  border-color: var(--orange);
}
.btn--primary:hover,
.btn--primary:focus-visible {
  background: #FF9147;
  border-color: #FF9147;
  box-shadow: 0 0 0 1px rgba(255, 122, 26, .5), 0 0 26px rgba(255, 122, 26, .38);
}

.btn--ghost {
  background: transparent;
  color: var(--cyan);
  border-color: var(--cyan-45);
}
.btn--ghost:hover,
.btn--ghost:focus-visible {
  background: var(--cyan-12);
  border-color: var(--cyan);
  box-shadow: 0 0 22px rgba(55, 242, 210, .22);
}

.btn--quiet {
  background: transparent;
  color: var(--glass);
  border-color: var(--grid-soft);
}
.btn--quiet:hover,
.btn--quiet:focus-visible {
  color: var(--text);
  border-color: var(--glass);
}

.header-cta { font-size: 13px; padding: 10px 16px; }

/* ---------- 07. 布局壳与章节 ---------- */
.container { width: var(--shell); margin-inline: auto; }
.container--narrow { width: min(860px, calc(100% - 48px)); }
.container--wide { width: min(1560px, calc(100% - 48px)); }

.section {
  position: relative;
  padding-block: clamp(48px, 7vw, 96px);
}
.section--tight { padding-block: clamp(30px, 4vw, 56px); }

.section--ink {
  background: var(--ink-900);
  border-block: 1px solid var(--grid-soft);
}

.section--paper,
.section--paper-warm {
  --text: #071426;
  --glass: #3C5A6E;
  --muted: #5C7285;
  --grid: #C9BCA7;
  --grid-soft: rgba(7, 20, 38, .14);
  --cyan: #0E7E6E;
  --cyan-12: rgba(14, 126, 110, .1);
  --cyan-24: rgba(14, 126, 110, .28);
  --cyan-45: rgba(14, 126, 110, .45);
  color: var(--text);
}
.section--paper { background: var(--paper-light); }
.section--paper-warm { background: var(--paper); }

/* ---------- 08. 文字层级 ---------- */
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--cyan);
}
.eyebrow::before {
  content: "";
  width: 26px;
  height: 1px;
  background: currentColor;
  flex: none;
}

.section-title {
  font-family: var(--font-display);
  font-size: clamp(28px, 4vw, 56px);
  font-weight: 800;
  line-height: 1.08;
  letter-spacing: -.01em;
  color: var(--text);
}

.lede {
  max-width: 62ch;
  margin-top: 16px;
  font-size: clamp(16px, 1.4vw, 19px);
  line-height: 1.78;
  color: var(--glass);
}

.mono {
  font-family: var(--font-mono);
  letter-spacing: .08em;
}

.num {
  font-family: var(--font-mono);
  font-weight: 600;
  letter-spacing: .04em;
  font-variant-numeric: tabular-nums;
}

.display-xl {
  font-family: var(--font-mono);
  font-size: clamp(72px, 12vw, 220px);
  font-weight: 600;
  line-height: .84;
  letter-spacing: .01em;
  color: var(--text);
}

/* ---------- 09. 面板与旁注 ---------- */
.glass-panel {
  position: relative;
  padding: clamp(20px, 3vw, 32px);
  background: linear-gradient(158deg, rgba(169, 199, 217, .14), rgba(169, 199, 217, .035));
  border: 1px solid rgba(169, 199, 217, .26);
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
}
.glass-panel::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 38px;
  height: 2px;
  background: var(--cyan);
}

.paper-panel {
  padding: clamp(20px, 3vw, 32px);
  background: var(--paper-light);
  color: #071426;
  border: 1px solid rgba(7, 20, 38, .12);
}

.note {
  padding-left: 16px;
  border-left: 2px solid var(--cyan-45);
  font-family: var(--font-serif);
  font-size: 15px;
  line-height: 1.85;
  color: var(--glass);
}

/* ---------- 10. 标签与状态 ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 9px;
  border: 1px solid var(--grid-soft);
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: .12em;
  line-height: 1.6;
  color: var(--glass);
  white-space: nowrap;
}

.status-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--cyan);
  flex: none;
}
.status-dot--cyan { background: var(--cyan); box-shadow: 0 0 9px rgba(55, 242, 210, .65); }
.status-dot--green { background: var(--green); box-shadow: 0 0 9px rgba(91, 227, 138, .6); }
.status-dot--amber { background: var(--amber); box-shadow: 0 0 9px rgba(245, 196, 81, .6); }

/* ---------- 11. 面包屑 ---------- */
.breadcrumb { margin-bottom: 22px; }

.breadcrumb-list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .1em;
  color: var(--muted);
}

.breadcrumb-item {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}
.breadcrumb-item + .breadcrumb-item::before {
  content: "/";
  color: var(--grid);
}
.breadcrumb-item a {
  color: var(--glass);
  text-decoration: none;
  transition: color var(--dur) var(--ease);
}
.breadcrumb-item a:hover,
.breadcrumb-item a:focus-visible { color: var(--cyan); }

.breadcrumb-current {
  color: var(--cyan);
  font-weight: 600;
}

/* ---------- 12. 记录清单行 ---------- */
.index-list { border-top: 1px solid var(--grid-soft); }

.index-row {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: 18px;
  padding: 15px 4px;
  border-bottom: 1px solid var(--grid-soft);
  transition: background var(--dur) var(--ease);
}
.index-row:hover { background: var(--cyan-12); }

.index-num {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: .12em;
  color: var(--cyan);
  white-space: nowrap;
}

.index-text {
  min-width: 0;
  font-size: 15px;
  line-height: 1.6;
  color: var(--text);
}

/* ---------- 13. 折叠问答 ---------- */
.accordion { border-top: 1px solid var(--grid-soft); }

.accordion-item { border-bottom: 1px solid var(--grid-soft); }

.accordion-trigger {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  width: 100%;
  padding: 18px 4px;
  text-align: left;
  font-family: var(--font-body);
  font-size: 17px;
  font-weight: 500;
  line-height: 1.6;
  color: var(--text);
  cursor: pointer;
  transition: color var(--dur) var(--ease);
}
.accordion-trigger::after {
  content: "+";
  flex: none;
  font-family: var(--font-mono);
  font-size: 20px;
  line-height: 1;
  color: var(--cyan);
  transition: transform var(--dur) var(--ease);
}
.accordion-trigger:hover,
.accordion-trigger:focus-visible { color: var(--cyan); }
.accordion-trigger[aria-expanded="true"]::after { transform: rotate(45deg); }

.accordion-panel {
  padding-bottom: 20px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--glass);
}
.accordion-panel[hidden] { display: none; }

/* ---------- 14. 图片容器 ---------- */
.media {
  position: relative;
  overflow: hidden;
  background: var(--ink-700);
  border: 1px solid var(--grid-soft);
}
.media > img,
.media > video {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.media--wide { aspect-ratio: 21 / 9; }
.media--16x9 { aspect-ratio: 16 / 9; }
.media--4x3 { aspect-ratio: 4 / 3; }
.media--1x1 { aspect-ratio: 1 / 1; }
.media--3x4 { aspect-ratio: 3 / 4; }

.media--placeholder::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(to right, rgba(55, 242, 210, .12) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(55, 242, 210, .12) 1px, transparent 1px);
  background-size: 42px 42px;
}

.media-frame {
  padding: 10px;
  border: 1px solid var(--grid-soft);
  background: rgba(169, 199, 217, .05);
}
.media-frame > .media { border: 0; }

.media-caption {
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.65;
  color: var(--muted);
}

/* ---------- 15. 滚动显现 ---------- */
html.has-js [data-reveal] {
  opacity: 0;
  transform: translateY(18px);
}
html.has-js [data-reveal].is-revealed {
  opacity: 1;
  transform: none;
  transition: opacity .55s var(--ease), transform .55s var(--ease);
}

/* ---------- 16. 页脚 ---------- */
.site-footer {
  position: relative;
  margin-top: auto;
  background: var(--ink-900);
  border-top: 1px solid var(--grid-soft);
}
.site-footer::before {
  content: "";
  display: block;
  height: 6px;
  background-image: repeating-linear-gradient(90deg, var(--grid) 0 1px, transparent 1px 48px);
  opacity: .85;
}

.footer-inner {
  width: var(--shell);
  margin-inline: auto;
  padding-block: clamp(40px, 5vw, 64px) 22px;
}

.footer-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.5fr) minmax(0, .72fr) minmax(0, .72fr) minmax(0, 1.2fr);
  gap: clamp(28px, 4vw, 56px);
}

.footer-brand-line {
  font-family: var(--font-display);
  font-size: clamp(18px, 2vw, 22px);
  font-weight: 800;
  letter-spacing: .03em;
  line-height: 1.35;
  color: var(--text);
}
.footer-brand-sep {
  color: var(--orange);
  margin-inline: 8px;
}

.footer-desc {
  margin-top: 14px;
  max-width: 34ch;
  font-size: 14px;
  line-height: 1.8;
  color: var(--glass);
}

.footer-badge-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin-top: 20px;
}

.footer-col-title {
  margin-bottom: 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--cyan);
}

.footer-links {
  display: grid;
  gap: 9px;
}

.footer-link {
  display: inline-block;
  font-size: 14px;
  line-height: 1.6;
  color: var(--glass);
  text-decoration: none;
  transition: color var(--dur) var(--ease), transform var(--dur) var(--ease);
}
.footer-link:hover,
.footer-link:focus-visible {
  color: var(--cyan);
  transform: translateX(3px);
}

.footer-contact {
  display: grid;
  gap: 14px;
}

.footer-contact-item {
  display: grid;
  gap: 3px;
}

.footer-contact-label {
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 600;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--muted);
}

.footer-contact-value {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  font-size: 14px;
  line-height: 1.6;
  color: var(--text);
  word-break: break-word;
}

.copy-btn {
  padding: 2px 8px;
  border: 1px solid var(--cyan-24);
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 600;
  letter-spacing: .12em;
  line-height: 1.8;
  cursor: pointer;
  transition: background var(--dur) var(--ease), border-color var(--dur) var(--ease), color var(--dur) var(--ease);
}
.copy-btn:hover,
.copy-btn:focus-visible {
  background: var(--cyan-12);
  border-color: var(--cyan);
}
.copy-btn.is-copied {
  background: rgba(91, 227, 138, .16);
  border-color: rgba(91, 227, 138, .6);
  color: var(--green);
}

.footer-note {
  margin-top: 18px;
  padding-left: 12px;
  border-left: 2px solid var(--grid-soft);
  font-size: 12px;
  line-height: 1.75;
  color: var(--muted);
}

.footer-bottom {
  margin-top: clamp(30px, 4vw, 48px);
  padding-top: 18px;
  border-top: 1px solid var(--grid-soft);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 24px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--muted);
}

.footer-legal { color: var(--glass); }

.footer-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 18px;
}

/* ---------- 17. 响应式 ---------- */
@media (max-width: 1180px) {
  .nav-cluster { gap: 14px; }
  .nav-link { padding-inline: 8px; }
  .header-actions { gap: 10px; }
}

@media (max-width: 1060px) {
  .brand-tagline { display: none; }
  .header-utility { display: none; }
  .header-inner { min-height: 70px; }
}

@media (max-width: 900px) {
  :root { --shell: min(100% - 40px, 860px); }

  body { background-attachment: scroll; }

  .nav-toggle { display: inline-flex; }

  .nav-cluster {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 8px 20px 26px;
    background: rgba(3, 10, 18, .98);
    -webkit-backdrop-filter: blur(18px);
    backdrop-filter: blur(18px);
    border-bottom: 1px solid var(--grid-soft);
    box-shadow: 0 28px 48px rgba(0, 0, 0, .55);
    max-height: calc(100vh - 70px);
    overflow-y: auto;
    overscroll-behavior: contain;
  }
  .nav-cluster[data-open] { display: flex; }

  .site-nav { width: 100%; }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    width: 100%;
  }
  .nav-list li { width: 100%; }

  .nav-link {
    display: block;
    padding: 14px 2px;
    font-size: 16px;
    color: var(--text);
    border-bottom: 1px solid rgba(43, 74, 94, .5);
  }
  .nav-link::after { display: none; }
  .nav-link[aria-current="page"] {
    color: var(--cyan);
    box-shadow: inset 2px 0 0 var(--cyan);
    padding-left: 12px;
  }

  .header-actions {
    flex-direction: column;
    align-items: stretch;
    gap: 12px;
    margin-top: 20px;
  }
  .header-utility {
    display: inline-flex;
    justify-content: center;
    padding: 12px;
    font-size: 14px;
    border: 1px dashed rgba(169, 199, 217, .35);
    border-bottom: 1px dashed rgba(169, 199, 217, .35);
  }
  .header-cta { padding: 14px 18px; font-size: 14px; }

  .footer-grid { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); }
  .footer-brand { grid-column: 1 / -1; }
  .footer-col:last-child { grid-column: 1 / -1; }
}

@media (max-width: 620px) {
  :root { --shell: calc(100% - 32px); }

  .brand { gap: 10px; }
  .brand-mark { width: 38px; height: 38px; font-size: 12px; }
  .brand-name { font-size: 18px; }
  .version-badge { font-size: 10px; padding: 4px 7px; letter-spacing: .08em; }
  .nav-toggle { padding: 8px 10px; }

  .footer-grid { grid-template-columns: minmax(0, 1fr); }
  .footer-bottom { flex-direction: column; align-items: flex-start; }
  .index-row { grid-template-columns: auto minmax(0, 1fr); }
  .index-row > :last-child { grid-column: 2; justify-self: start; }
}

/* ---------- 18. 减少动效 ---------- */
@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.has-js [data-reveal] {
    opacity: 1;
    transform: none;
  }

  .footer-link:hover,
  .footer-link:focus-visible { transform: none; }

  .btn:active { transform: none; }
}