/* ==========================================================================
   博鱼体育 · 共享样式表 /assets/site.css
   新未来主义：深色舱底 · 细发光边界 · 等宽数值轨道
   ========================================================================== */
:root {
  --color-surface: #2d2b2f;
  --color-surface-alt: #3b393e;
  --color-surface-deep: #4d4b50;
  --color-ink: #cec9d4;
  --color-ink-soft: #9d94a8;
  --color-ink-muted: #81778d;
  --color-line: #4a474d;
  --color-primary: #9961db;
  --color-primary-ink: #141118;
  --color-primary-soft: #3c3347;
  --color-accent: #93f807;
  --color-accent-ink: #141118;
  --color-highlight: #3f5028;
  --color-focus: #94ff00;
  --color-contrast-surface: #f3f2f4;
  --color-contrast-ink: #353338;
  --color-contrast-line: #c9c8cb;
  --color-contrast-accent: #497c04;
  --overlay-scrim: linear-gradient(180deg, rgba(243, 242, 244, 0.35) 0%, rgba(243, 242, 244, 0.72) 55%, rgba(243, 242, 244, 0.92) 100%);
  --font-heading: "PingFang SC", "HarmonyOS Sans SC", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-body: "PingFang SC", "HarmonyOS Sans SC", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --text-xs: 12.2px;
  --text-sm: 15.2px;
  --text-base: 17px;
  --text-lg: 21.2px;
  --text-xl: 26.6px;
  --text-2xl: 33.2px;
  --text-3xl: 41.5px;
  --text-4xl: 51.9px;
  --text-display: clamp(53px, 10.9vw, 140px);
  --text-figure: clamp(44px, 7.9vw, 101px);
  --weight-heading: 739;
  --weight-body: 400;
  --leading-body: 1.67;
  --leading-heading: 1.28;
  --tracking-heading: -0.007em;
  --radius-sm: 10px;
  --radius-md: 14px;
  --radius-lg: 18px;
  --radius-pill: 999px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: 0 0 0 1px rgba(147, 248, 7, 0.35);
  --shadow-2: 0 0 28px rgba(147, 248, 7, 0.35);
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1160px;
  --measure: 66ch;
  --gutter: 32px;
  --section-y: 100px;
  --section-y-lg: 140px;
}

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

/* ---------- 基座 ---------- */
body {
  min-height: 100vh;
  background-color: var(--color-surface);
  background-image:
    radial-gradient(1100px 520px at 6% -12%, color-mix(in srgb, var(--color-primary) 20%, transparent), transparent 70%),
    radial-gradient(820px 460px at 98% 2%, color-mix(in srgb, var(--color-accent) 8%, transparent), transparent 70%);
  background-repeat: no-repeat;
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: var(--weight-body);
  line-height: var(--leading-body);
  letter-spacing: 0.012em;
  overflow-x: hidden;
}
h1, h2, h3, h4 {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}
h1 { font-size: var(--text-3xl); }
h2 { font-size: var(--text-2xl); }
h3 { font-size: var(--text-xl); }
h4 { font-size: var(--text-lg); }
::selection { background: var(--color-accent); color: var(--color-accent-ink); }
:focus-visible { outline: 2px solid var(--color-focus); outline-offset: 3px; border-radius: 4px; }
#main-content { outline: none; }

/* ---------- 跳转链接 ---------- */
.skip-link {
  position: absolute;
  left: var(--space-3);
  top: -80px;
  z-index: 200;
  padding: 10px 20px;
  border-radius: var(--radius-sm);
  background: var(--color-accent);
  color: var(--color-accent-ink);
  font-size: var(--text-sm);
  letter-spacing: 0.06em;
  transition: top 0.2s ease;
}
.skip-link:focus { top: var(--space-2); }

/* ---------- 容器与栅格 ---------- */
.shell {
  width: 100%;
  max-width: calc(var(--container) + var(--gutter) * 2);
  margin-inline: auto;
  padding-inline: var(--gutter);
}
.grid {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--gutter);
}
.col-2 { grid-column: span 2; }
.col-3 { grid-column: span 3; }
.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-9 { grid-column: span 9; }
.col-12 { grid-column: span 12; }
.stack { display: flex; flex-direction: column; gap: var(--space-3); }
.cluster { display: flex; flex-wrap: wrap; align-items: center; gap: var(--space-2); }

/* ---------- 区块节奏 ---------- */
.section { padding-block: var(--section-y); }
.section--lg { padding-block: var(--section-y-lg); }
.section--tight { padding-block: var(--space-8); }
.band-contrast {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}
.band-contrast h1,
.band-contrast h2,
.band-contrast h3,
.band-contrast h4 { color: var(--color-contrast-ink); }
.band-contrast a { color: var(--color-contrast-accent); }
.band-contrast .num,
.band-contrast .eyebrow { color: var(--color-contrast-accent); }
.rule { height: 1px; border: 0; background: var(--color-line); }
.rule--offset { margin-left: clamp(0px, 8%, 96px); }
.band-contrast .rule { background: var(--color-contrast-line); }

/* ==========================================================================
   头部刊头
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 80;
  background: color-mix(in srgb, var(--color-surface) 91%, transparent);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
  border-bottom: var(--border-thin) solid color-mix(in srgb, var(--color-accent) 22%, var(--color-line));
  box-shadow: 0 0 26px color-mix(in srgb, var(--color-accent) 12%, transparent);
  transition: box-shadow 0.3s ease;
}
.site-header[data-open] {
  box-shadow: 0 0 34px color-mix(in srgb, var(--color-accent) 28%, transparent);
}
.read-progress {
  position: fixed;
  inset: 0 0 auto 0;
  height: 2px;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background: var(--color-accent);
  box-shadow: 0 0 12px color-mix(in srgb, var(--color-accent) 70%, transparent);
  opacity: 0;
  transition: opacity 0.3s ease;
  pointer-events: none;
  z-index: 120;
}

.masthead {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
  align-items: center;
  gap: var(--space-3);
  padding-block: var(--space-4) var(--space-3);
  transition: padding-block 0.3s ease;
}
.masthead__brand { grid-column: 2; justify-self: center; text-align: center; }

.brand { display: inline-flex; align-items: center; gap: var(--space-2); }
.brand__mark {
  display: inline-grid;
  place-items: center;
  width: 42px;
  height: 42px;
  border-radius: var(--radius-sm);
  background: color-mix(in srgb, var(--color-primary) 24%, var(--color-surface-alt));
  border: var(--border-thin) solid color-mix(in srgb, var(--color-primary) 62%, transparent);
  box-shadow: 0 0 18px color-mix(in srgb, var(--color-primary) 32%, transparent);
  color: var(--color-primary);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.04em;
}
.brand__id { display: flex; flex-direction: column; align-items: flex-start; }
.brand__name {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-xl);
  letter-spacing: 0.02em;
  line-height: 1.1;
}
.brand__tag {
  display: block;
  margin-top: 3px;
  max-height: 24px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  color: var(--color-ink-muted);
  transition: opacity 0.3s ease, max-height 0.3s ease, margin 0.3s ease;
}

.site-header[data-scrolled] .masthead { padding-block: var(--space-2); }
.site-header[data-scrolled] .brand__tag {
  opacity: 0;
  max-height: 0;
  margin-top: 0;
}

.header-search {
  grid-column: 3;
  justify-self: end;
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 8px 14px;
  border-radius: var(--radius-pill);
  border: var(--border-thin) solid var(--color-line);
  color: var(--color-ink-soft);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  transition: color 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}
.header-search:hover,
.header-search:focus-visible {
  color: var(--color-ink);
  border-color: color-mix(in srgb, var(--color-accent) 50%, transparent);
  box-shadow: var(--shadow-1);
}
.header-search__glyph { font-family: var(--font-mono); color: var(--color-accent); font-size: var(--text-sm); }

.nav-bar {
  position: relative;
  border-top: var(--border-thin) solid var(--color-line);
}
.nav-bar__inner {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-3);
  min-height: 54px;
}
.site-nav { width: 100%; }
.nav__list {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-1);
}
.nav__link {
  display: block;
  padding: 9px 15px;
  border-radius: var(--radius-pill);
  border: var(--border-thin) solid transparent;
  font-size: var(--text-sm);
  letter-spacing: 0.07em;
  color: var(--color-ink-soft);
  transition: color 0.2s ease, border-color 0.2s ease, background 0.2s ease;
}
.nav__link:hover {
  color: var(--color-ink);
  border-color: color-mix(in srgb, var(--color-primary) 58%, transparent);
}
.nav__link[aria-current="page"] {
  color: var(--color-accent);
  border-color: color-mix(in srgb, var(--color-accent) 58%, transparent);
  background: color-mix(in srgb, var(--color-accent) 9%, transparent);
  box-shadow: 0 0 18px color-mix(in srgb, var(--color-accent) 22%, transparent);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 10px;
  padding: 9px 16px;
  border-radius: var(--radius-pill);
  border: var(--border-thin) solid var(--color-line);
  color: var(--color-ink-soft);
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  transition: color 0.2s ease, border-color 0.2s ease;
}
.nav-toggle:hover { color: var(--color-ink); border-color: color-mix(in srgb, var(--color-accent) 50%, transparent); }
.nav-toggle__bars { position: relative; display: block; width: 18px; height: 12px; }
.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  width: 100%;
  height: 1px;
  background: currentColor;
  transition: transform 0.25s ease, top 0.25s ease;
}
.nav-toggle__bars::before { top: 0; }
.nav-toggle__bars::after { top: 11px; }
.site-header[data-open] .nav-toggle__bars::before { top: 6px; transform: rotate(45deg); }
.site-header[data-open] .nav-toggle__bars::after { top: 6px; transform: rotate(-45deg); }

/* ==========================================================================
   页脚
   ========================================================================== */
.site-footer {
  margin-top: var(--section-y);
  padding-block: var(--space-8) var(--space-6);
  background: var(--color-surface-alt);
  border-top: var(--border-thin) solid color-mix(in srgb, var(--color-accent) 24%, var(--color-line));
  box-shadow: 0 -1px 0 color-mix(in srgb, var(--color-accent) 18%, transparent);
  color: var(--color-ink);
  font-size: var(--text-sm);
}
.footer-top {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-2);
}
.footer-brand {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-2xl);
  letter-spacing: var(--tracking-heading);
}
.footer-brand__sub {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
}
.footer-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: var(--space-6) var(--gutter);
  margin-top: var(--space-4);
  padding-top: var(--space-6);
  border-top: var(--border-thin) solid var(--color-line);
}
.footer-col__title {
  position: relative;
  margin-bottom: var(--space-3);
  padding-left: 16px;
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  letter-spacing: 0.16em;
  color: var(--color-ink-soft);
}
.footer-col__title::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.5em;
  width: 6px;
  height: 6px;
  border-radius: 2px;
  background: var(--color-accent);
  box-shadow: 0 0 10px color-mix(in srgb, var(--color-accent) 80%, transparent);
}
.footer-list li + li { margin-top: 10px; }
.footer-list a {
  color: var(--color-ink);
  border-bottom: 1px solid transparent;
  transition: color 0.2s ease, border-color 0.2s ease;
}
.footer-list a:hover {
  color: var(--color-accent);
  border-bottom-color: color-mix(in srgb, var(--color-accent) 55%, transparent);
}
.footer-contact { margin-top: var(--space-3); display: grid; gap: 4px; }
.footer-contact dt {
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  color: var(--color-ink-muted);
}
.footer-contact dd {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  line-height: 1.5;
  color: var(--color-ink);
  word-break: break-word;
}
.footer-contact dd + dt { margin-top: 10px; }
.footer-note {
  margin-top: var(--space-3);
  font-size: var(--text-xs);
  line-height: 1.75;
  color: var(--color-ink-muted);
}
.footer-icp {
  margin-top: var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.06em;
  color: var(--color-accent);
}
.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  margin-top: var(--space-6);
  padding-top: var(--space-3);
  border-top: var(--border-thin) solid var(--color-line);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}
.footer-statement { max-width: 52ch; line-height: 1.7; }
.footer-icp-line { font-family: var(--font-mono); letter-spacing: 0.06em; }
.footer-copy { font-family: var(--font-mono); letter-spacing: 0.06em; }

/* ==========================================================================
   通用组件
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 12px 24px;
  border-radius: var(--radius-pill);
  border: var(--border-thin) solid transparent;
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  letter-spacing: 0.08em;
  transition: background 0.2s ease, color 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}
.btn--primary {
  background: var(--color-primary);
  color: var(--color-primary-ink);
  box-shadow: var(--shadow-1);
}
.btn--primary:hover { background: color-mix(in srgb, var(--color-primary) 84%, var(--color-contrast-surface)); }
.btn--accent {
  background: var(--color-accent);
  color: var(--color-accent-ink);
  box-shadow: var(--shadow-2);
}
.btn--accent:hover { background: color-mix(in srgb, var(--color-accent) 82%, var(--color-contrast-surface)); }
.btn--ghost {
  border-color: color-mix(in srgb, var(--color-primary) 58%, transparent);
  color: var(--color-ink);
}
.btn--ghost:hover {
  border-color: color-mix(in srgb, var(--color-accent) 55%, transparent);
  color: var(--color-accent);
}

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
}
.breadcrumb a { color: var(--color-ink-muted); }
.breadcrumb a:hover { color: var(--color-accent); }
.breadcrumb__sep { font-family: var(--font-mono); color: var(--color-primary); }
.breadcrumb [aria-current="page"] { color: var(--color-ink-soft); }

.prose {
  max-width: var(--measure);
  color: var(--color-ink);
  font-size: var(--text-base);
  line-height: var(--leading-body);
}
.prose p + p { margin-top: var(--space-3); }
.prose h2 { margin-top: var(--space-8); margin-bottom: var(--space-2); }
.prose h3 { margin-top: var(--space-6); margin-bottom: var(--space-2); }
.prose ul, .prose ol { margin-top: var(--space-2); padding-left: 1.2em; list-style: disc; }
.prose li + li { margin-top: 6px; }
.prose a {
  color: var(--color-primary);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-thickness: 1px;
}
.prose a:hover { color: var(--color-accent); }
.prose strong { font-weight: var(--weight-heading); color: var(--color-ink); }

.panel {
  background: var(--color-surface-alt);
  border-radius: var(--radius-md);
  padding: var(--space-4);
  box-shadow: var(--shadow-1);
}
.panel--deep { background: var(--color-surface-deep); box-shadow: none; }
.panel--glow {
  border: var(--border-thin) solid color-mix(in srgb, var(--color-accent) 42%, transparent);
  box-shadow: var(--shadow-2);
}
.panel--glow:hover { border-color: color-mix(in srgb, var(--color-accent) 70%, transparent); }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.26em;
  text-transform: uppercase;
  color: var(--color-accent);
}
.section-number {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-3xl);
  line-height: 1;
  letter-spacing: 0.02em;
  color: color-mix(in srgb, var(--color-primary) 72%, var(--color-ink-muted));
}

.num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.02em;
  color: var(--color-accent);
}
.num--md { font-size: var(--text-3xl); line-height: 1.05; }
.num--lg { font-size: var(--text-figure); line-height: 0.94; }

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 5px 13px;
  border-radius: var(--radius-pill);
  background: var(--color-primary-soft);
  color: var(--color-ink);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
}
.tag--accent {
  background: var(--color-highlight);
  color: var(--color-accent);
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--color-accent) 34%, transparent);
}

.kv {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-3);
  padding: 12px 0;
  border-bottom: var(--border-thin) solid var(--color-line);
}
.kv__key { font-size: var(--text-sm); color: var(--color-ink-soft); }
.kv__val {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.02em;
  color: var(--color-ink);
  text-align: right;
}

.accordion { display: flex; flex-direction: column; gap: var(--space-2); }
.accordion__item {
  background: var(--color-surface-alt);
  border-radius: var(--radius-md);
  box-shadow: 0 0 0 1px var(--color-line);
  transition: box-shadow 0.3s ease, background 0.3s ease;
}
.accordion__item[data-open] {
  box-shadow: var(--shadow-1), inset 0 0 32px color-mix(in srgb, var(--color-accent) 8%, transparent);
}
.accordion__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  width: 100%;
  padding: 18px var(--space-4);
  text-align: left;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-lg);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}
.accordion__head:hover { color: var(--color-accent); }
.accordion__icon {
  flex: none;
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  line-height: 1;
  color: var(--color-accent);
  transition: transform 0.3s ease;
}
.accordion__item[data-open] .accordion__icon { transform: rotate(45deg); }
.accordion__panel {
  padding: 0 var(--space-4) var(--space-4);
  font-size: var(--text-sm);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}
.accordion__panel[hidden] { display: none; }

/* ---------- 图片容器基础规则 ---------- */
.media-frame {
  position: relative;
  isolation: isolate;
  overflow: hidden;
  border-radius: var(--radius-lg);
  background: var(--color-surface-alt);
  box-shadow: var(--shadow-1);
}
.media-frame--16x9 { aspect-ratio: 16 / 9; }
.media-frame--4x5 { aspect-ratio: 4 / 5; }
.media-frame--21x9 { aspect-ratio: 21 / 9; }
.media-frame__img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: saturate(0.86) contrast(1.06);
}
.media-frame__placeholder {
  position: absolute;
  inset: 0;
  background-color: var(--color-surface-deep);
  background-image:
    linear-gradient(120deg, color-mix(in srgb, var(--color-primary) 26%, transparent) 0 1px, transparent 1px 100%),
    linear-gradient(60deg, color-mix(in srgb, var(--color-accent) 12%, transparent) 0 1px, transparent 1px 100%);
  background-size: 46px 46px, 68px 68px;
}
.media-frame__scrim {
  position: absolute;
  inset: 0;
  background: var(--overlay-scrim);
  z-index: 1;
}
.media-frame__body {
  position: absolute;
  inset: auto 0 0 0;
  z-index: 2;
  padding: var(--space-4);
  color: var(--color-contrast-ink);
}
.media-frame__body h2,
.media-frame__body h3 { color: var(--color-contrast-ink); }
.media-frame__caption {
  display: inline-block;
  margin-bottom: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-contrast-accent);
}

/* ==========================================================================
   响应式
   ========================================================================== */
@media (max-width: 980px) {
  .grid { grid-template-columns: repeat(6, minmax(0, 1fr)); gap: var(--space-3); }
  .col-2, .col-3, .col-4 { grid-column: span 3; }
  .col-5, .col-6, .col-7 { grid-column: span 6; }
  .col-8, .col-9, .col-12 { grid-column: span 6; }
}
@media (max-width: 900px) {
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: var(--space-4) var(--space-3); }

  .nav-bar__inner { justify-content: space-between; }
  .nav-toggle { display: inline-flex; }
  .site-nav {
    display: none;
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    padding: var(--space-2) var(--gutter) var(--space-4);
    background: var(--color-surface-alt);
    border-top: var(--border-thin) solid var(--color-line);
    border-bottom: var(--border-thin) solid color-mix(in srgb, var(--color-accent) 28%, var(--color-line));
    box-shadow: 0 30px 50px -26px color-mix(in srgb, var(--color-surface) 90%, black);
  }
  .site-nav[data-open] { display: block; animation: navDrop 0.24s ease-out both; }
  .nav__list { flex-direction: column; align-items: stretch; gap: 4px; }
  .nav__link {
    padding: 13px 16px;
    border-radius: var(--radius-sm);
    font-size: var(--text-base);
    background: color-mix(in srgb, var(--color-surface) 60%, transparent);
  }
  .nav__link[aria-current="page"] {
    background: color-mix(in srgb, var(--color-accent) 12%, transparent);
  }
}
@keyframes navDrop {
  from { opacity: 0; transform: translateY(-8px); }
  to { opacity: 1; transform: translateY(0); }
}
@media (max-width: 760px) {
  .masthead {
    grid-template-columns: minmax(0, 1fr) auto;
    padding-block: var(--space-3);
  }
  .masthead__brand { grid-column: 1; justify-self: start; text-align: left; }
  .header-search { grid-column: 2; }
  .header-search__text { display: none; }
  .header-search { padding: 9px 12px; }
  .brand__mark { width: 36px; height: 36px; font-size: var(--text-xs); }
  .brand__name { font-size: var(--text-lg); }
  .brand__tag { display: none; }
}
@media (max-width: 620px) {
  .grid { grid-template-columns: minmax(0, 1fr); }
  .col-2, .col-3, .col-4, .col-5, .col-6, .col-7, .col-8, .col-9, .col-12 { grid-column: span 1; }
  .footer-grid { grid-template-columns: minmax(0, 1fr); gap: var(--space-4); }
  .footer-bottom { flex-direction: column; align-items: flex-start; }
  .footer-top { flex-direction: column; }
  .section { padding-block: var(--space-8); }
  .section--lg { padding-block: var(--space-8); }
  .panel { padding: var(--space-3); }
  .media-frame__body { padding: var(--space-3); }
}

/* ==========================================================================
   动效与可访问性
   ========================================================================== */
@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;
    scroll-behavior: auto !important;
  }
  .site-nav[data-open] { animation: none; }
}