/* ==========================================================================
   MANBETX 城市坐标 · 共享外壳样式 / site.css
   结构：令牌 → 重置与排版 → 工具类 → 头部侧轨 → 移动抽屉 → 页脚 → 通用组件
   ========================================================================== */

:root {
  /* 色彩：深墨蓝明度阶梯 + 荧光青 + 琥珀 */
  --ink-950: #061320;
  --ink-900: #0A1B2A;
  --ink-800: #102636;
  --ink-700: #1B3A50;
  --mist-300: #9DB2C4;
  --text-hi: #E8EFF6;
  --text-mid: #CFDCE8;
  --paper-050: #F3EEE3;
  --paper-ink: #1B2A36;
  --paper-link: #0D6B66;
  --cyan-400: #3FE3D2;
  --cyan-300: #62F0E4;
  --teal-600: #17AFA6;
  --amber-400: #FFA23A;
  --amber-100: #FFE2BE;

  /* 尺度 */
  --rail-w: 88px;
  --header-h-mobile: 58px;
  --gutter: clamp(18px, 4vw, 56px);
  --max-w: 1440px;
  --measure: 720px;

  /* 动效 */
  --dur: 200ms;
  --dur-slow: 240ms;
  --ease: cubic-bezier(.22, .7, .3, 1);

  /* 形状 */
  --radius-lg: 28px;
  --radius-md: 16px;
  --radius-sm: 10px;
  --pill: 999px;
  --shadow-panel: 0 24px 60px -32px rgba(0, 0, 0, .85);

  /* 字体栈（无远程加载，全部本地回退） */
  --font-display: "Barlow Condensed", "Arial Narrow", "Helvetica Neue", "Noto Sans SC", "PingFang SC", sans-serif;
  --font-body: "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

/* ---------- 重置 ---------- */
*,
*::before,
*::after { box-sizing: border-box; }

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

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

ul, ol { padding: 0; }

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

button, input, textarea, select { font: inherit; color: inherit; }

/* ---------- 基础排版 ---------- */
html { background: var(--ink-950); }

body {
  min-height: 100vh;
  background: var(--ink-950);
  color: var(--text-hi);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.75;
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

p + p { margin-top: 1.1em; }

h1, h2, h3, h4 {
  font-family: var(--font-body);
  font-weight: 700;
  line-height: 1.18;
  letter-spacing: -.01em;
  color: var(--text-hi);
}

h1 { font-size: clamp(2.2rem, 5vw, 4.5rem); }
h2 { font-size: clamp(1.5rem, 2.6vw, 2rem); }
h3 { font-size: clamp(1.05rem, 1.6vw, 1.375rem); }

a {
  color: inherit;
  text-decoration: none;
  transition: color var(--dur) var(--ease);
}

a:hover { color: var(--cyan-400); }

strong, b { font-weight: 700; }

hr {
  border: 0;
  height: 1px;
  background: var(--ink-700);
  margin: 2rem 0;
}

::selection {
  background: var(--cyan-400);
  color: #04222a;
}

/* 桌面端为固定竖轨让位 */
@media (min-width: 900px) {
  body { padding-left: var(--rail-w); }
}

@media (max-width: 899px) {
  body { padding-top: var(--header-h-mobile); }
}

@media (prefers-reduced-motion: no-preference) {
  html { scroll-behavior: smooth; }
}

#main-content { scroll-margin-top: 76px; }

/* ---------- 焦点 ---------- */
:focus-visible {
  outline: 2px solid var(--cyan-400);
  outline-offset: 2px;
  border-radius: 4px;
}

/* ---------- 工具类 ---------- */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: .02em;
}

.container {
  width: 100%;
  max-width: var(--max-w);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-display);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .3em;
  text-transform: uppercase;
  color: var(--mist-300);
}

.eyebrow::before {
  content: "";
  width: 20px;
  height: 1px;
  background: var(--cyan-400);
  flex: 0 0 auto;
}

/* ---------- 跳转链接 ---------- */
.skip-link {
  position: absolute;
  top: 0;
  left: 0;
  z-index: 999;
  width: max-content;
  min-width: 168px;
  padding: 12px 18px;
  background: var(--cyan-400);
  color: #04222a;
  font-size: 14px;
  font-weight: 700;
  letter-spacing: .06em;
  border-radius: 0 0 var(--radius-md) 0;
  transform: translateY(-110%);
  transition: transform var(--dur) var(--ease);
}

.skip-link:focus,
.skip-link:focus-visible {
  transform: translateY(0);
  outline: none;
}

/* ==========================================================================
   头部 · 桌面竖轨
   ========================================================================== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 80;
  width: var(--rail-w);
  display: flex;
  flex-direction: column;
  background: var(--ink-950);
  border-right: 1px solid var(--ink-700);
}

/* 品牌铭牌 */
.rail-brand {
  position: relative;
  flex: 0 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  padding: 20px 6px 16px;
  border-bottom: 1px solid var(--ink-700);
}

.rail-brand::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: -5px;
  width: 1px;
  height: 9px;
  background: var(--cyan-400);
  transform: translateX(-50%);
  opacity: .85;
}

.brand {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  color: var(--paper-050);
}

.brand:hover { color: var(--cyan-400); }

.brand__mark {
  writing-mode: vertical-rl;
  text-orientation: mixed;
  font-family: var(--font-display);
  font-size: 15px;
  font-weight: 700;
  line-height: 1;
  letter-spacing: .2em;
  text-transform: uppercase;
  white-space: nowrap;
}

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

.rail-coord {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: .04em;
  color: var(--mist-300);
  opacity: .78;
  white-space: nowrap;
  text-align: center;
}

/* 竖排导航 */
.rail-nav {
  flex: 1 1 auto;
  min-height: 0;
  display: flex;
  flex-direction: column;
  padding: 14px 0 0;
  overflow-y: auto;
  overflow-x: hidden;
  scrollbar-width: thin;
  scrollbar-color: var(--ink-700) transparent;
}

.rail-nav::-webkit-scrollbar { width: 4px; }
.rail-nav::-webkit-scrollbar-thumb {
  background: var(--ink-700);
  border-radius: 4px;
}

.rail-nav__list {
  list-style: none;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 0 4px;
}

.rail-nav__link {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  width: 100%;
  padding: 10px 2px;
  border-radius: var(--radius-md);
  color: var(--mist-300);
  font-size: 13px;
  font-weight: 500;
  letter-spacing: .12em;
  text-align: center;
  transition: color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.rail-nav__tick {
  display: block;
  width: 12px;
  height: 2px;
  border-radius: 2px;
  background: var(--ink-700);
  transition: width var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.rail-nav__label {
  writing-mode: vertical-rl;
  text-orientation: mixed;
  line-height: 1.15;
  white-space: nowrap;
}

.rail-nav__link:hover {
  color: var(--text-hi);
  background: var(--ink-900);
}

.rail-nav__link:hover .rail-nav__tick {
  width: 24px;
  background: var(--cyan-400);
}

.rail-nav__link[aria-current="page"] {
  color: var(--cyan-400);
  background: var(--ink-900);
}

.rail-nav__link[aria-current="page"] .rail-nav__tick {
  width: 24px;
  background: var(--cyan-400);
}

.rail-nav__link[aria-current="page"]::after {
  content: "";
  position: absolute;
  left: -4px;
  top: 50%;
  width: 3px;
  height: 26px;
  border-radius: 0 3px 3px 0;
  background: var(--cyan-400);
  transform: translateY(-50%);
}

/* 侧轨 CTA */
.rail-nav__actions {
  margin-top: auto;
  padding: 16px 0 22px;
  display: flex;
  justify-content: center;
  border-top: 1px solid var(--ink-700);
}

.rail-cta {
  display: block;
  writing-mode: vertical-rl;
  text-orientation: mixed;
  padding: 18px 9px;
  border-radius: var(--pill);
  background: var(--cyan-400);
  color: #04222a;
  font-size: 12.5px;
  font-weight: 700;
  line-height: 1;
  letter-spacing: .18em;
  text-align: center;
  box-shadow: 0 0 0 0 rgba(63, 227, 210, .35);
  transition: background-color var(--dur) var(--ease), box-shadow var(--dur) var(--ease), color var(--dur) var(--ease);
}

.rail-cta:hover,
.rail-cta:focus-visible {
  background: var(--cyan-300);
  color: #04222a;
  box-shadow: 0 0 0 6px rgba(63, 227, 210, .14);
}

.rail-cta:active {
  background: var(--teal-600);
  color: #04222a;
}

/* 移动端按钮（桌面隐藏） */
.nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  padding: 0;
  border: 1px solid var(--ink-700);
  border-radius: 14px;
  background: var(--ink-900);
  color: var(--text-hi);
  cursor: pointer;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.nav-toggle:hover { border-color: var(--ink-700); background: var(--ink-800); }

.nav-toggle__line {
  display: block;
  width: 18px;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  transition: transform var(--dur) var(--ease), width var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.nav-toggle__line:last-of-type { width: 11px; }

.nav-toggle[aria-expanded="true"] {
  color: var(--cyan-400);
  border-color: var(--cyan-400);
  background: var(--ink-900);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__line:first-of-type {
  transform: translateY(3.5px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__line:last-of-type {
  width: 18px;
  transform: translateY(-3.5px) rotate(-45deg);
}

/* 滚动进度水银柱 */
.scroll-meter {
  --p: 0;
  position: absolute;
  top: 0;
  right: 0;
  width: 3px;
  height: calc(var(--p) * 1%);
  border-radius: 0 0 3px 3px;
  background: linear-gradient(180deg, var(--cyan-400), var(--teal-600));
  pointer-events: none;
  transition: height 120ms linear;
}

/* ==========================================================================
   头部 · 移动端顶栏与抽屉
   ========================================================================== */
@media (max-width: 899px) {
  .site-header {
    inset: 0 0 auto 0;
    width: auto;
    height: var(--header-h-mobile);
    display: grid;
    grid-template-columns: 1fr auto;
    align-items: center;
    padding: 0 12px;
    border-right: 0;
    border-bottom: 1px solid var(--ink-700);
    background: rgba(6, 19, 32, .97);
  }

  .rail-brand {
    grid-column: 1;
    justify-self: start;
    flex-direction: row;
    align-items: baseline;
    gap: 12px;
    padding: 0;
    border-bottom: 0;
  }

  .rail-brand::after { display: none; }

  .brand {
    flex-direction: row;
    align-items: baseline;
    gap: 10px;
  }

  .brand__mark {
    writing-mode: horizontal-tb;
    font-size: 16px;
    letter-spacing: .22em;
  }

  .nav-toggle {
    grid-column: 2;
    justify-self: end;
    display: flex;
  }

  .rail-nav {
    position: fixed;
    top: var(--header-h-mobile);
    left: 0;
    width: min(84vw, 340px);
    max-height: calc(100vh - var(--header-h-mobile));
    padding: 8px 0 22px;
    background: var(--ink-950);
    border-right: 1px solid var(--ink-700);
    border-bottom: 1px solid var(--ink-700);
    border-radius: 0 var(--radius-lg) var(--radius-lg) 0;
    box-shadow: var(--shadow-panel);
    z-index: 70;
    transform: translateX(-104%);
    visibility: hidden;
    opacity: 0;
    transition: transform 220ms var(--ease), opacity 180ms var(--ease), visibility 0s linear 220ms;
  }

  .rail-nav[data-open] {
    transform: translateX(0);
    visibility: visible;
    opacity: 1;
    transition: transform 220ms var(--ease), opacity 180ms var(--ease), visibility 0s linear 0s;
  }

  .rail-nav__list {
    align-items: stretch;
    gap: 2px;
    padding: 0 12px;
  }

  .rail-nav__link {
    flex-direction: row;
    align-items: center;
    justify-content: flex-start;
    gap: 14px;
    padding: 14px 12px;
    border-radius: 14px;
    font-size: 15px;
    letter-spacing: .05em;
    text-align: left;
  }

  .rail-nav__label { writing-mode: horizontal-tb; }

  .rail-nav__tick { width: 14px; }

  .rail-nav__link:hover .rail-nav__tick,
  .rail-nav__link[aria-current="page"] .rail-nav__tick { width: 26px; }

  .rail-nav__link[aria-current="page"]::after { display: none; }

  .rail-nav__actions {
    margin-top: 14px;
    padding: 16px 24px 0;
    justify-content: flex-start;
    border-top: 1px solid var(--ink-700);
  }

  .rail-cta {
    writing-mode: horizontal-tb;
    padding: 13px 24px;
    font-size: 14px;
    letter-spacing: .08em;
  }

  .scroll-meter {
    top: auto;
    bottom: -1px;
    right: 0;
    left: 0;
    width: calc(var(--p) * 1%);
    height: 2px;
    border-radius: 0 3px 3px 0;
    background: linear-gradient(90deg, var(--cyan-400), var(--teal-600));
    transition: width 120ms linear;
  }

  .site-header.is-nav-open { background: var(--ink-950); }
}

/* ==========================================================================
   页脚
   ========================================================================== */
.site-footer {
  position: relative;
  margin-top: clamp(56px, 8vw, 120px);
  background: var(--ink-950);
  border-top: 1px solid var(--ink-700);
  color: var(--mist-300);
  font-size: 15px;
}

.site-footer::before {
  content: "";
  display: block;
  height: 9px;
  background-image: repeating-linear-gradient(90deg, var(--ink-700) 0 1px, transparent 1px 20px);
  background-repeat: repeat-x;
  opacity: .9;
}

.footer__inner {
  max-width: var(--max-w);
  margin-inline: auto;
  padding: clamp(40px, 6vw, 72px) var(--gutter) clamp(30px, 4vw, 48px);
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(28px, 4vw, 48px);
}

.footer__lead { display: flex; flex-direction: column; gap: 10px; }

.footer__brand {
  font-family: var(--font-display);
  font-size: clamp(26px, 3.2vw, 38px);
  font-weight: 700;
  line-height: 1;
  letter-spacing: .06em;
  text-transform: uppercase;
  color: var(--paper-050);
}

.footer__brand:hover { color: var(--cyan-400); }

.footer__brand-sub {
  margin: 0;
  font-size: 12px;
  letter-spacing: .3em;
  color: var(--mist-300);
  opacity: .78;
}

.footer__tagline {
  margin: 8px 0 0;
  max-width: 26ch;
  font-size: 17px;
  line-height: 1.6;
  color: var(--text-mid);
}

.footer__version {
  margin: 4px 0 0;
  font-size: 12.5px;
  line-height: 1.7;
  color: var(--mist-300);
  opacity: .82;
}

.footer__version .mono { color: var(--amber-400); }

.footer__col { min-width: 0; }

.footer__col-title {
  margin: 0 0 16px;
  font-size: 12px;
  font-weight: 500;
  letter-spacing: .3em;
  text-transform: uppercase;
  color: var(--mist-300);
  opacity: .7;
}

.footer__links {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 11px;
}

.footer__links a {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 15px;
  color: var(--text-mid);
  transition: color var(--dur) var(--ease);
}

.footer__links a::before {
  content: "";
  flex: 0 0 auto;
  width: 10px;
  height: 1px;
  background: var(--ink-700);
  transition: width var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.footer__links a:hover { color: var(--cyan-400); }

.footer__links a:hover::before {
  width: 22px;
  background: var(--cyan-400);
}

.footer__contact { min-width: 0; }

.footer__dl {
  margin: 0;
  display: grid;
  gap: 14px;
  font-size: 14px;
  line-height: 1.6;
}

.footer__dl-row { display: grid; gap: 3px; min-width: 0; }

.footer__dl dt {
  font-size: 11px;
  letter-spacing: .22em;
  color: var(--mist-300);
  opacity: .62;
}

.footer__dl dd {
  margin: 0;
  color: var(--text-mid);
  word-break: break-word;
}

.footer__dl dd.mono {
  font-size: 13.5px;
  color: var(--amber-400);
}

.footer__base {
  max-width: var(--max-w);
  margin-inline: auto;
  padding: 22px var(--gutter) 34px;
  border-top: 1px solid var(--ink-700);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px 28px;
  font-size: 13px;
  line-height: 1.7;
  color: var(--mist-300);
}

.footer__note { margin: 0; flex: 1 1 280px; max-width: 54ch; }

.footer__legal {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 20px;
}

.footer__legal a {
  color: var(--mist-300);
  padding-bottom: 2px;
  border-bottom: 1px solid transparent;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.footer__legal a:hover,
.footer__legal a:focus-visible {
  color: var(--cyan-400);
  border-bottom-color: var(--cyan-400);
}

.footer__meta {
  margin: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 6px 20px;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 12px;
  letter-spacing: .02em;
  color: var(--mist-300);
  opacity: .82;
}

.footer__icp { color: var(--mist-300); }

@media (min-width: 640px) {
  .footer__inner { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer__lead { grid-column: 1 / -1; }
}

@media (min-width: 1100px) {
  .footer__inner {
    grid-template-columns: minmax(240px, 1.5fr) minmax(120px, .75fr) minmax(120px, .75fr) minmax(200px, 1fr);
  }
  .footer__lead { grid-column: auto; }
}

/* ==========================================================================
   通用按钮
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 14px 26px;
  border: 1px solid transparent;
  border-radius: var(--pill);
  font-family: var(--font-body);
  font-size: 15px;
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: .02em;
  text-align: center;
  cursor: pointer;
  transition: background-color var(--dur) var(--ease), color var(--dur) var(--ease),
              border-color var(--dur) var(--ease), box-shadow var(--dur) var(--ease);
}

.btn--primary {
  background: var(--cyan-400);
  color: #04222a;
}

.btn--primary:hover,
.btn--primary:focus-visible {
  background: var(--cyan-300);
  color: #04222a;
  box-shadow: 0 0 0 6px rgba(63, 227, 210, .14);
}

.btn--primary:active {
  background: var(--teal-600);
  color: #04222a;
}

.btn--ghost {
  background: transparent;
  color: var(--text-hi);
  border-color: var(--ink-700);
}

.btn--ghost:hover,
.btn--ghost:focus-visible {
  color: var(--cyan-400);
  border-color: var(--cyan-400);
  background: var(--ink-900);
}

.btn--sm {
  padding: 10px 18px;
  font-size: 13px;
}

/* ==========================================================================
   面包屑
   ========================================================================== */
.breadcrumb { padding: 0; }

.breadcrumb__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--mist-300);
}

.breadcrumb__item { display: inline-flex; align-items: center; }

.breadcrumb__item + .breadcrumb__item::before {
  content: "/";
  margin-inline: 10px;
  color: var(--ink-700);
}

.breadcrumb__link { color: var(--mist-300); }
.breadcrumb__link:hover { color: var(--cyan-400); }

.breadcrumb__item[aria-current="page"] { color: var(--text-mid); }

/* ==========================================================================
   布局与内容容器
   ========================================================================== */
.layout-split {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 4vw, 56px);
}

@media (min-width: 1024px) {
  .layout-split {
    grid-template-columns: minmax(260px, 1fr) minmax(0, 2.4fr);
    align-items: start;
  }
}

.layout-aside {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 3vw, 40px);
}

@media (min-width: 900px) {
  .layout-aside { grid-template-columns: minmax(200px, 1fr) minmax(0, 3.6fr); }
}

.prose {
  max-width: var(--measure);
  font-size: 16px;
  line-height: 1.85;
  color: var(--text-mid);
}

.prose > * + * { margin-top: 1.1em; }

.prose h2 {
  margin-top: 2em;
  font-size: clamp(1.25rem, 2.2vw, 1.75rem);
  color: var(--text-hi);
}

.prose h3 {
  margin-top: 1.6em;
  color: var(--text-hi);
}

.prose ul,
.prose ol { padding-left: 1.3em; }

.prose li + li { margin-top: .5em; }

.prose a {
  color: var(--cyan-400);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

.prose strong { color: var(--text-hi); }

.sheet {
  background: var(--paper-050);
  color: var(--paper-ink);
  border-radius: var(--radius-lg);
  padding: clamp(22px, 4vw, 48px);
}

.sheet h2,
.sheet h3,
.sheet h4,
.sheet strong { color: var(--paper-ink); }

.sheet .prose,
.sheet p { color: #2A3A46; }

.sheet a {
  color: var(--paper-link);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.sheet a:hover { color: #084B47; }

/* ==========================================================================
   图片容器基础规则（页面阶段放置占位或 img）
   ========================================================================== */
.img-frame {
  position: relative;
  display: block;
  overflow: hidden;
  border-radius: var(--radius-md);
  background-color: var(--ink-800);
  background-image:
    linear-gradient(150deg, rgba(63, 227, 210, .12), transparent 58%),
    repeating-linear-gradient(0deg, rgba(27, 58, 80, .85) 0 1px, transparent 1px 32px),
    repeating-linear-gradient(90deg, rgba(27, 58, 80, .85) 0 1px, transparent 1px 32px);
  isolation: isolate;
}

.img-frame > img {
  position: relative;
  z-index: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.img-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 1;
  background: linear-gradient(180deg, rgba(6, 19, 32, 0) 42%, rgba(6, 19, 32, .72) 100%);
  pointer-events: none;
}

.img-frame--16x9 { aspect-ratio: 16 / 9; }
.img-frame--4x3 { aspect-ratio: 4 / 3; }
.img-frame--1x1 { aspect-ratio: 1 / 1; }

.img-frame__timecode {
  position: absolute;
  top: 10px;
  right: 10px;
  z-index: 2;
  padding: 3px 8px;
  border-radius: 6px;
  border: 1px solid rgba(255, 162, 58, .35);
  background: rgba(6, 19, 32, .84);
  color: var(--amber-400);
  font-family: var(--font-mono);
  font-size: 11px;
  font-variant-numeric: tabular-nums;
  letter-spacing: .06em;
}

/* ==========================================================================
   减少动效
   ========================================================================== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
    transition-delay: 0s !important;
    scroll-behavior: auto !important;
  }

  .rail-nav,
  .rail-nav[data-open] {
    transition: none !important;
  }
}