/* ==========================================================================
   仲博客户端 · 索引台  /assets/site.css
   共享外壳：reset / 变量 / 中文排版 / 头部 / 页脚 / 通用组件
   ========================================================================== */

/* ---------- 1. Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body, h1, h2, h3, h4, h5, p, ul, ol, li, figure, blockquote, dl, dd { margin: 0; padding: 0; }
ul, ol { list-style: none; }
img, svg, video { display: block; max-width: 100%; }
button { font: inherit; color: inherit; background: none; border: 0; }
a { color: inherit; text-decoration: none; }
table { border-collapse: collapse; width: 100%; }

/* ---------- 2. 设计变量 ---------- */
:root {
  --ink-900: #070B14;
  --ink-800: #0E1A2B;
  --ink-700: #14263D;
  --celadon: #7FBFA6;
  --celadon-deep: #3E7C68;
  --amber: #F2A93B;
  --amber-soft: #FFD08A;
  --mist: #D8E3EF;
  --index-gray: #8FA3B8;
  --alert: #E05C5C;

  --line: 1px solid rgba(127, 191, 166, 0.20);
  --line-soft: 1px solid rgba(127, 191, 166, 0.12);
  --amber-line: 1px solid rgba(242, 169, 59, 0.38);

  --font-serif: "Noto Serif SC", "Source Han Serif SC", "Songti SC", "STSong", serif;
  --font-sans: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: "JetBrains Mono", "Roboto Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;

  --radius-sm: 10px;
  --radius-md: 16px;
  --radius-lg: 22px;
  --radius-pill: 999px;

  --shell: 1200px;
  --gutter: clamp(1.05rem, 4vw, 2rem);
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

/* ---------- 3. 基础排版与氛围 ---------- */
body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background-color: var(--ink-900);
  color: var(--mist);
  font-family: var(--font-sans);
  font-size: 17px;
  line-height: 1.7;
  letter-spacing: 0.012em;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background:
    radial-gradient(58vw 58vw at 10% -12%, rgba(127, 191, 166, 0.11), transparent 62%),
    radial-gradient(48vw 48vw at 106% 6%, rgba(242, 169, 59, 0.08), transparent 66%),
    radial-gradient(70vw 55vw at 50% 118%, rgba(20, 38, 61, 0.85), transparent 72%);
}
main, .site-main { position: relative; z-index: 1; flex: 1 0 auto; }

h1, h2, h3, h4 { font-weight: 800; line-height: 1.2; letter-spacing: 0.01em; text-wrap: balance; }
p { text-wrap: pretty; }
::selection { background: rgba(242, 169, 59, 0.32); color: #FFFFFF; }

:focus-visible {
  outline: 2px solid var(--amber-soft);
  outline-offset: 3px;
  border-radius: 6px;
}

.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.04em;
}
.eyebrow {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--celadon);
}
.lede {
  font-size: clamp(1.04rem, 1.5vw, 1.2rem);
  line-height: 1.75;
  color: #C6D6E7;
  max-width: 60ch;
}
.prose { max-width: 68ch; font-size: 1.01rem; color: #C2D2E3; }
.prose p { margin: 0 0 1.05em; }
.prose h2 { font-family: var(--font-serif); font-size: 1.5rem; margin: 1.7em 0 0.6em; color: #EAF2FA; }
.prose h3 { font-size: 1.14rem; margin: 1.5em 0 0.5em; color: #EAF2FA; }
.prose ul, .prose ol { list-style: disc; padding-left: 1.25em; margin: 0 0 1.1em; }
.prose ol { list-style: decimal; }
.prose li { margin-bottom: 0.4em; }
.prose a { color: var(--celadon); border-bottom: 1px solid rgba(127, 191, 166, 0.45); }
.prose a:hover { color: var(--amber-soft); border-bottom-color: var(--amber-soft); }
.prose strong { color: #EAF2FA; }
.prose code { font-family: var(--font-mono); font-size: 0.88em; color: var(--amber-soft); background: rgba(242, 169, 59, 0.10); padding: 0.12em 0.42em; border-radius: 6px; }

/* ---------- 4. 布局工具 ---------- */
.shell { width: min(var(--shell), 92vw); margin-inline: auto; }
.shell--narrow { width: min(760px, 92vw); margin-inline: auto; }
.shell--wide { width: min(1320px, 94vw); margin-inline: auto; }
.section { padding-block: clamp(2.6rem, 6vw, 4.6rem); }
.section--tight { padding-block: clamp(1.6rem, 4vw, 2.8rem); }

.grid { display: grid; gap: clamp(1rem, 2.4vw, 1.6rem); }
.grid--2 { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.grid--3 { grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); }
.grid--4 { grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); }

.section-head { display: grid; gap: 0.55rem; margin-bottom: clamp(1.5rem, 3vw, 2.3rem); }
.section-head__index { font-family: var(--font-mono); font-size: 0.76rem; letter-spacing: 0.26em; color: var(--amber); }
.section-head__title {
  font-family: var(--font-serif);
  font-weight: 900;
  font-size: clamp(1.8rem, 4vw, 3.2rem);
  line-height: 1.14;
  color: #EAF2FA;
}
.section-head__note { color: var(--index-gray); font-size: 0.97rem; max-width: 62ch; }

/* ---------- 5. 按钮与链接 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.66rem 1.15rem;
  border: 1px solid transparent;
  border-radius: var(--radius-pill);
  font-family: var(--font-sans);
  font-weight: 700;
  font-size: 0.92rem;
  line-height: 1.2;
  cursor: pointer;
  white-space: nowrap;
  transition: background-color 0.18s var(--ease), color 0.18s var(--ease),
              border-color 0.18s var(--ease), box-shadow 0.18s var(--ease), transform 0.18s var(--ease);
}
.btn--primary {
  background: var(--amber);
  color: #17100A;
  box-shadow: 0 14px 30px -18px rgba(242, 169, 59, 0.95);
}
.btn--primary:hover { background: var(--amber-soft); transform: translateY(-1px); }
.btn--ghost {
  background: rgba(127, 191, 166, 0.08);
  color: var(--celadon);
  border-color: rgba(127, 191, 166, 0.42);
}
.btn--ghost:hover { background: rgba(127, 191, 166, 0.17); color: #EAF7F1; border-color: var(--celadon); }
.btn--quiet {
  background: transparent;
  color: var(--index-gray);
  border-color: rgba(143, 163, 184, 0.30);
}
.btn--quiet:hover { color: var(--mist); border-color: rgba(143, 163, 184, 0.65); }
.btn--sm { padding: 0.5rem 0.9rem; font-size: 0.84rem; }
.btn--block { width: 100%; }

/* ---------- 6. 跳至主内容 ---------- */
.skip-link {
  position: absolute;
  left: 50%;
  top: -120px;
  transform: translateX(-50%);
  z-index: 99;
  background: var(--amber);
  color: #17100A;
  font-weight: 800;
  padding: 0.62rem 1.1rem;
  border-radius: 0 0 12px 12px;
  transition: top 0.18s var(--ease);
}
.skip-link:focus { top: 0; }

/* ---------- 7. 页头 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(7, 11, 20, 0.94);
  border-bottom: var(--line);
  backdrop-filter: blur(10px);
}
.header-rail {
  border-bottom: var(--line-soft);
  background: linear-gradient(90deg, rgba(127, 191, 166, 0.07), rgba(242, 169, 59, 0.05));
}
.header-rail__inner {
  width: min(var(--shell), 92vw);
  margin-inline: auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.42rem 0;
}
.header-rail__mark {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  color: var(--celadon);
}
.header-rail__meta { font-size: 0.7rem; letter-spacing: 0.16em; color: var(--index-gray); }

.masthead__inner {
  width: min(var(--shell), 92vw);
  margin-inline: auto;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 1rem;
  padding: 1.05rem 0 0.95rem;
}
.masthead__coord {
  justify-self: start;
  font-size: 0.7rem;
  letter-spacing: 0.22em;
  color: var(--index-gray);
}
.masthead__brand {
  grid-column: 2;
  display: grid;
  gap: 0.15rem;
  text-align: center;
  justify-items: center;
}
.masthead__kicker {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.3em;
  color: var(--celadon);
}
.masthead__logo {
  font-family: var(--font-serif);
  font-weight: 900;
  font-size: clamp(1.5rem, 3.4vw, 2.45rem);
  line-height: 1.1;
  color: #F1F7FD;
  transition: color 0.18s var(--ease);
}
.masthead__brand:hover .masthead__logo { color: var(--amber-soft); }
.masthead__tagline { font-size: 0.78rem; letter-spacing: 0.06em; color: var(--index-gray); }
.masthead__actions { grid-column: 3; justify-self: end; display: flex; gap: 0.5rem; }

.nav-toggle {
  display: none;
  align-items: center;
  gap: 0.55rem;
  padding: 0.5rem 0.8rem;
  border: 1px solid rgba(127, 191, 166, 0.38);
  border-radius: var(--radius-pill);
  color: var(--celadon);
  font-size: 0.82rem;
  font-weight: 700;
  cursor: pointer;
}
.nav-toggle__bars { display: grid; gap: 4px; width: 16px; }
.nav-toggle__bars span { display: block; height: 2px; background: currentColor; border-radius: 2px; transition: transform 0.2s var(--ease), opacity 0.2s var(--ease); }
.nav-toggle.is-open .nav-toggle__bars span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.nav-toggle.is-open .nav-toggle__bars span:nth-child(2) { opacity: 0; }
.nav-toggle.is-open .nav-toggle__bars span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }
.nav-toggle:hover { color: var(--amber-soft); border-color: var(--amber-soft); }

.site-nav { border-bottom: var(--line); }
.site-nav__list {
  width: min(var(--shell), 92vw);
  margin-inline: auto;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: clamp(0.6rem, 2vw, 1.7rem);
  padding: 0.62rem 0;
}
.site-nav__link {
  position: relative;
  display: inline-block;
  padding: 0.32rem 0.1rem;
  font-size: 0.92rem;
  color: var(--mist);
  transition: color 0.18s var(--ease);
}
.site-nav__link::after {
  content: "";
  position: absolute;
  left: 0.1rem;
  right: 0.1rem;
  bottom: 0.1rem;
  height: 2px;
  background: var(--amber);
  transform: scaleX(0);
  transform-origin: center;
  transition: transform 0.2s var(--ease), background-color 0.2s var(--ease);
}
.site-nav__link:hover { color: #FFFFFF; }
.site-nav__link:hover::after { transform: scaleX(1); }
.site-nav__link[aria-current="page"] { color: var(--amber-soft); }
.site-nav__link[aria-current="page"]::after { transform: scaleX(1); background: var(--celadon); }

.scroll-progress {
  position: absolute;
  left: 0;
  right: 0;
  bottom: -1px;
  height: 2px;
  pointer-events: none;
}
.scroll-progress__bar {
  display: block;
  height: 100%;
  width: 0;
  background: linear-gradient(90deg, var(--celadon), var(--amber));
  transition: width 0.1s linear;
}

/* ---------- 8. 页脚 ---------- */
.site-footer {
  position: relative;
  z-index: 1;
  margin-top: clamp(3rem, 7vw, 6rem);
  background: var(--ink-800);
  border-top: var(--line);
  overflow: hidden;
}
.site-footer::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(127, 191, 166, 0.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(127, 191, 166, 0.06) 1px, transparent 1px);
  background-size: 68px 68px;
  -webkit-mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.85), transparent 78%);
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.85), transparent 78%);
}
.footer-frame {
  position: relative;
  width: min(var(--shell), 92vw);
  margin-inline: auto;
  padding: clamp(2.2rem, 5vw, 3.6rem) 0 1.5rem;
}
.footer-index { display: flex; align-items: center; gap: 1rem; margin-bottom: clamp(1.6rem, 4vw, 2.6rem); }
.footer-index__line { flex: 1; height: 1px; background: linear-gradient(90deg, rgba(127, 191, 166, 0.6), rgba(127, 191, 166, 0.05)); }
.footer-index__code { font-size: 0.7rem; letter-spacing: 0.26em; color: var(--celadon-deep); }

.footer-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1.6fr;
  gap: clamp(1.5rem, 3vw, 2.6rem);
}
.footer-brand__kicker { font-size: 0.7rem; letter-spacing: 0.28em; color: var(--celadon); }
.footer-brand__logo {
  font-family: var(--font-serif);
  font-weight: 900;
  font-size: clamp(1.35rem, 2.6vw, 1.85rem);
  color: #F1F7FD;
  margin: 0.35rem 0 0.6rem;
}
.footer-brand__summary { font-size: 0.92rem; line-height: 1.75; color: #AFC1D4; max-width: 34ch; }
.legend--footer { margin-top: 1.1rem; }

.footer-col__title {
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.2em;
  color: var(--amber);
  margin-bottom: 0.85rem;
}
.footer-col__list { display: grid; gap: 0.5rem; }
.footer-link {
  display: inline-block;
  font-size: 0.94rem;
  color: #BDCEDF;
  padding: 0.1rem 0;
  border-bottom: 1px solid transparent;
  transition: color 0.18s var(--ease), border-color 0.18s var(--ease);
}
.footer-link:hover { color: var(--celadon); border-bottom-color: rgba(127, 191, 166, 0.6); }

.footer-col--contact { display: grid; gap: 0.7rem; }
.contact-list { display: grid; gap: 0.6rem; }
.contact-list__item {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  padding-bottom: 0.55rem;
  border-bottom: var(--line-soft);
}
.contact-list__label {
  flex: none;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.16em;
  color: var(--index-gray);
}
.contact-list__value { font-size: 0.9rem; color: var(--mist); word-break: break-word; }
.copy-btn {
  flex: none;
  padding: 0.2rem 0.6rem;
  border: 1px solid rgba(242, 169, 59, 0.42);
  border-radius: var(--radius-pill);
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--amber);
  cursor: pointer;
  transition: background-color 0.18s var(--ease), color 0.18s var(--ease), border-color 0.18s var(--ease);
}
.copy-btn:hover { background: rgba(242, 169, 59, 0.16); color: var(--amber-soft); }
.copy-btn[data-copied="true"] { background: var(--celadon); border-color: var(--celadon); color: #06201A; }
.footer-contact__note { font-size: 0.84rem; line-height: 1.7; color: var(--index-gray); }

.footer-base {
  margin-top: clamp(1.8rem, 4vw, 2.8rem);
  padding-top: 1.1rem;
  border-top: var(--line-soft);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.7rem 1.4rem;
  font-size: 0.84rem;
  color: var(--index-gray);
}
.footer-base__links { display: flex; flex-wrap: wrap; gap: 0.6rem 1.2rem; }
.footer-base__links a { color: #AFC1D4; border-bottom: 1px solid rgba(143, 163, 184, 0.35); }
.footer-base__links a:hover { color: var(--amber-soft); border-bottom-color: var(--amber-soft); }
.footer-base__icp { font-size: 0.76rem; letter-spacing: 0.1em; color: var(--index-gray); }

.to-top {
  position: fixed;
  right: clamp(0.9rem, 3vw, 2rem);
  bottom: clamp(0.9rem, 3vw, 2rem);
  z-index: 60;
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.55rem 0.95rem;
  border: var(--amber-line);
  border-radius: var(--radius-pill);
  background: rgba(14, 26, 43, 0.92);
  color: var(--amber);
  font-size: 0.82rem;
  font-weight: 700;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: opacity 0.2s var(--ease), transform 0.2s var(--ease), visibility 0.2s linear, color 0.18s var(--ease), border-color 0.18s var(--ease);
}
.to-top[data-visible="true"] { opacity: 1; visibility: visible; transform: none; }
.to-top:hover { color: #17100A; background: var(--amber); border-color: var(--amber); }
.to-top__mark { font-family: var(--font-mono); }

/* ---------- 9. 通用组件 ---------- */
.breadcrumbs { padding-top: clamp(1rem, 3vw, 1.8rem); }
.breadcrumbs__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.76rem;
  letter-spacing: 0.06em;
  color: var(--index-gray);
}
.breadcrumbs__item { display: inline-flex; align-items: center; gap: 0.5rem; }
.breadcrumbs__item:not(:last-child)::after { content: "›"; color: var(--celadon-deep); }
.breadcrumbs__link { color: var(--celadon); }
.breadcrumbs__link:hover { color: var(--amber-soft); text-decoration: underline; }
.breadcrumbs__current { color: var(--mist); }

.panel {
  position: relative;
  background: var(--ink-700);
  border: var(--line);
  border-radius: var(--radius-lg);
  padding: clamp(1.15rem, 2.6vw, 1.85rem);
  overflow: hidden;
}
.panel::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: radial-gradient(130% 90% at 100% 0%, rgba(242, 169, 59, 0.09), transparent 62%);
}
.panel > * { position: relative; }

.index-card {
  position: relative;
  display: grid;
  gap: 0.65rem;
  align-content: start;
  padding: clamp(1.05rem, 2.2vw, 1.4rem);
  background: linear-gradient(158deg, rgba(20, 38, 61, 0.95), rgba(14, 26, 43, 0.96));
  border: var(--line);
  border-radius: var(--radius-md);
  transition: border-color 0.2s var(--ease), transform 0.2s var(--ease), box-shadow 0.2s var(--ease);
}
.index-card::after {
  content: "";
  position: absolute;
  left: 0;
  top: 1.1rem;
  width: 3px;
  height: 1.6rem;
  border-radius: 0 3px 3px 0;
  background: var(--celadon);
}
.index-card:hover {
  border-color: rgba(127, 191, 166, 0.55);
  transform: translateY(-3px);
  box-shadow: 0 26px 44px -32px rgba(0, 0, 0, 0.95);
}
.index-card--amber::after { background: var(--amber); }
.index-card--amber { border-color: var(--amber-line); }
.index-card__no { font-family: var(--font-mono); font-size: 0.72rem; letter-spacing: 0.22em; color: var(--celadon); }
.index-card__title { font-size: 1.06rem; font-weight: 800; color: #EAF2FA; }
.index-card__meta { font-family: var(--font-mono); font-size: 0.74rem; letter-spacing: 0.08em; color: var(--index-gray); }
.index-card__body { font-size: 0.93rem; line-height: 1.7; color: #B7C8DA; }
.index-card__tags { display: flex; flex-wrap: wrap; gap: 0.4rem; }

.tag {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.22rem 0.6rem;
  border: 1px solid rgba(127, 191, 166, 0.42);
  border-radius: var(--radius-pill);
  background: rgba(127, 191, 166, 0.08);
  color: var(--celadon);
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.08em;
}
.tag--amber { border-color: rgba(242, 169, 59, 0.55); background: rgba(242, 169, 59, 0.12); color: var(--amber-soft); }
.tag--alert { border-color: rgba(224, 92, 92, 0.55); background: rgba(224, 92, 92, 0.12); color: #F0A3A3; }
.tag--muted { border-color: rgba(143, 163, 184, 0.35); background: rgba(143, 163, 184, 0.08); color: var(--index-gray); }

.fold {
  background: rgba(20, 38, 61, 0.62);
  border: var(--line);
  border-radius: var(--radius-sm);
  overflow: hidden;
  transition: border-color 0.2s var(--ease);
}
.fold + .fold { margin-top: 0.7rem; }
.fold:hover { border-color: rgba(127, 191, 166, 0.42); }
.fold__trigger {
  display: flex;
  width: 100%;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.9rem;
  padding: 1rem 1.1rem;
  text-align: left;
  font-weight: 700;
  font-size: 0.99rem;
  color: var(--mist);
  cursor: pointer;
  transition: background-color 0.18s var(--ease), color 0.18s var(--ease);
}
.fold__trigger:hover { background: rgba(127, 191, 166, 0.09); color: #EAF2FA; }
.fold__trigger[aria-expanded="true"] { color: var(--amber-soft); }
.fold__mark { flex: none; font-family: var(--font-mono); color: var(--amber); transition: transform 0.2s var(--ease); }
.fold__trigger[aria-expanded="true"] .fold__mark { transform: rotate(45deg); }
.fold__panel { padding: 0 1.1rem 1.1rem; font-size: 0.95rem; line-height: 1.75; color: #B7C8DA; }
.fold__panel[hidden] { display: none; }

.legend { display: flex; flex-wrap: wrap; gap: 0.5rem 1.1rem; }
.legend__item {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  font-family: var(--font-mono);
  font-size: 0.74rem;
  letter-spacing: 0.08em;
  color: var(--index-gray);
}
.legend__dot { flex: none; width: 0.6rem; height: 0.6rem; border-radius: 50%; background: var(--index-gray); }
.legend__dot--celadon { background: var(--celadon); box-shadow: 0 0 0 3px rgba(127, 191, 166, 0.18); }
.legend__dot--amber { background: var(--amber); box-shadow: 0 0 0 3px rgba(242, 169, 59, 0.16); }
.legend__dot--alert { background: var(--alert); box-shadow: 0 0 0 3px rgba(224, 92, 92, 0.16); }

.media-frame {
  position: relative;
  aspect-ratio: 16 / 10;
  overflow: hidden;
  border: var(--line);
  border-radius: var(--radius-md);
  background: linear-gradient(150deg, var(--ink-700), var(--ink-900));
}
.media-frame img { width: 100%; height: 100%; object-fit: cover; }
.media-frame--wide { aspect-ratio: 21 / 9; }
.media-frame--tall { aspect-ratio: 3 / 4; }
.media-frame--square { aspect-ratio: 1 / 1; }
.media-frame__label {
  position: absolute;
  left: 0.75rem;
  bottom: 0.75rem;
  padding: 0.25rem 0.65rem;
  border-radius: var(--radius-pill);
  background: rgba(7, 11, 20, 0.78);
  border: var(--line-soft);
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.12em;
  color: var(--celadon);
}

/* ---------- 10. 动效与可见性 ---------- */
.has-js [data-reveal] {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.42s var(--ease), transform 0.42s var(--ease);
}
.has-js [data-reveal][data-revealed="true"] { opacity: 1; transform: none; }

/* ---------- 11. 响应式 ---------- */
@media (max-width: 1080px) {
  .footer-grid { grid-template-columns: 1.4fr 1fr 1.6fr; }
  .footer-col--contact { grid-column: 1 / -1; }
}

@media (max-width: 900px) {
  body { font-size: 16.5px; }
  .masthead__inner {
    grid-template-columns: 1fr auto;
    grid-template-areas:
      "brand toggle"
      "actions actions";
    row-gap: 0.85rem;
    padding: 0.95rem 0 0.85rem;
  }
  .masthead__coord { display: none; }
  .masthead__brand { grid-area: brand; justify-self: start; text-align: left; justify-items: start; }
  .masthead__actions { grid-area: actions; justify-self: stretch; width: 100%; }
  .masthead__actions .btn { flex: 1 1 0; }
  .nav-toggle { grid-area: toggle; display: inline-flex; }

  .site-nav {
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    background: rgba(14, 26, 43, 0.99);
    border-bottom: var(--line);
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    pointer-events: none;
    transition: max-height 0.24s var(--ease), opacity 0.18s var(--ease);
  }
  .site-nav[data-open="true"] {
    max-height: 72vh;
    opacity: 1;
    pointer-events: auto;
    overflow-y: auto;
    box-shadow: 0 30px 60px -30px rgba(0, 0, 0, 0.95);
  }
  .site-nav__list { flex-direction: column; align-items: stretch; gap: 0; padding: 0.4rem 1.15rem 1.1rem; }
  .site-nav__item + .site-nav__item { border-top: var(--line-soft); }
  .site-nav__link { display: block; padding: 0.85rem 0.15rem; font-size: 1.02rem; }
  .site-nav__link::after { display: none; }

  .footer-grid { grid-template-columns: 1fr 1fr; }
  .footer-brand { grid-column: 1 / -1; }
  .footer-col--contact { grid-column: 1 / -1; }
}

@media (max-width: 620px) {
  .header-rail__meta { display: none; }
  .header-rail__inner { justify-content: flex-start; }
  .masthead__tagline { display: none; }
  .footer-grid { grid-template-columns: 1fr; }
  .footer-base { flex-direction: column; align-items: flex-start; }
  .to-top__text { display: none; }
}

/* ---------- 12. 减少动效偏好 ---------- */
@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;
  }
  .has-js [data-reveal] { opacity: 1; transform: none; }
  .index-card:hover { transform: none; }
  .btn--primary:hover { transform: none; }
}