/* ==========================================================================
   196体育主站 · 共享样式表 /assets/site.css
   主题：夜间球场档案室 —— 暗场聚光、记分牌数字、档案抽屉、展签
   ========================================================================== */

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

html {
  background: var(--ink);
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

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

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

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

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

a { color: var(--ice); text-decoration: none; }
a:hover { color: var(--paper); }

/* ---------- 变量 ---------- */
:root {
  --ink: #0B0F0E;
  --ink-2: #0E2A22;
  --ink-3: #123B2E;
  --ink-4: #16493A;

  --flare: #FF4D2E;
  --flare-soft: #FF7A1A;
  --blue: #2D9CFF;
  --ice: #7FD4FF;
  --paper: #F4F7F5;
  --moss: #8AA39A;
  --amber: #FFC24B;

  --line: rgba(138, 163, 154, .22);
  --line-strong: rgba(138, 163, 154, .42);

  --r-xl: 34px;
  --r-lg: 24px;
  --r-md: 16px;
  --r-pill: 999px;

  --gutter: clamp(18px, 4vw, 44px);
  --maxw: 1220px;
  --measure: 68ch;

  --font-head: 'Archivo Black', 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-body: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'JetBrains Mono', 'Roboto Mono', 'Courier New', monospace;

  --ease: cubic-bezier(.2, .75, .3, 1);
  --dur: 220ms;
  --shadow: 0 26px 60px -34px rgba(0, 0, 0, .92);
}

/* ---------- 基础排版 ---------- */
body {
  min-height: 100vh;
  color: var(--paper);
  font-family: var(--font-body);
  font-size: clamp(16px, .35vw + 15.2px, 17.5px);
  line-height: 1.75;
  letter-spacing: .005em;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
  background-color: var(--ink);
  background-image:
    radial-gradient(58% 40% at 16% -8%, rgba(255, 77, 46, .18), transparent 68%),
    radial-gradient(48% 42% at 90% 4%, rgba(45, 156, 255, .16), transparent 70%),
    radial-gradient(120% 55% at 50% 108%, rgba(18, 59, 46, .85), transparent 72%);
  background-repeat: no-repeat;
  background-attachment: fixed;
}

body::-webkit-scrollbar { width: 10px; }
body::-webkit-scrollbar-track { background: #080C0B; }
body::-webkit-scrollbar-thumb { background: var(--ink-3); border-radius: 99px; }
body::-webkit-scrollbar-thumb:hover { background: var(--flare); }

h1, h2, h3, h4 {
  font-family: var(--font-head);
  font-weight: 900;
  line-height: 1.08;
  letter-spacing: -.02em;
  color: var(--paper);
  text-wrap: balance;
}

h1 { font-size: clamp(2.4rem, 5.2vw + 1rem, 6.6rem); line-height: 1; }
h2 { font-size: clamp(1.7rem, 3.6vw, 3rem); }
h3 { font-size: clamp(1.15rem, 1.8vw, 1.5rem); line-height: 1.25; }
h4 { font-size: 1.05rem; line-height: 1.4; }

p { text-wrap: pretty; }

strong { color: var(--paper); font-weight: 800; }

::selection { background: var(--flare); color: #170604; }

:focus-visible {
  outline: 2px solid var(--ice);
  outline-offset: 3px;
}

#main-content { display: block; scroll-margin-top: 140px; }

/* ---------- 跳转链接 ---------- */
.skip-link {
  position: fixed;
  left: var(--gutter);
  top: -120px;
  z-index: 200;
  padding: .7em 1.2em;
  border-radius: var(--r-pill);
  background: var(--amber);
  color: #1A1200;
  font-weight: 800;
  font-size: .9rem;
  transition: top var(--dur) var(--ease);
}

.skip-link:focus { top: 14px; }

/* ---------- 容器与工具 ---------- */
.wrap {
  width: min(var(--maxw), calc(100% - var(--gutter) * 2));
  margin-inline: auto;
}

.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: -.01em;
}

.section { padding-block: clamp(34px, 6vw, 76px); }

.section__head {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: 1rem 2rem;
  margin-bottom: clamp(20px, 3vw, 34px);
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: .6em;
  font-family: var(--font-mono);
  font-size: .76rem;
  letter-spacing: .22em;
  text-transform: uppercase;
  color: var(--flare);
}

.eyebrow::before {
  content: "";
  width: 26px;
  height: 2px;
  background: currentColor;
}

.lead {
  font-size: clamp(1.04rem, 1.5vw, 1.26rem);
  color: #D5E1DC;
  max-width: var(--measure);
}

.prose > * + * { margin-top: 1.05em; }
.prose p { max-width: var(--measure); }
.prose ul,
.prose ol { padding-left: 1.25em; max-width: var(--measure); }
.prose li + li { margin-top: .4em; }

.stack > * + * { margin-top: var(--stack, 1rem); }

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: .5em;
  padding: .8em 1.5em;
  border: 1px solid transparent;
  border-radius: var(--r-pill);
  font-weight: 800;
  font-size: .95rem;
  letter-spacing: .02em;
  text-decoration: none;
  cursor: pointer;
  transition: transform var(--dur) var(--ease),
              background-color var(--dur) var(--ease),
              border-color var(--dur) var(--ease),
              color var(--dur) var(--ease);
}

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

.btn--flare { background: var(--flare); color: #170604; }
.btn--flare:hover { background: var(--flare-soft); color: #170604; }

.btn--blue { background: var(--blue); color: #04141F; }
.btn--blue:hover { background: var(--ice); color: #04141F; }

.btn--ghost {
  background: transparent;
  border-color: var(--line-strong);
  color: var(--paper);
}
.btn--ghost:hover { border-color: var(--flare); color: var(--flare); }

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

/* ---------- 标签与斜切签 ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: .4em;
  padding: .34em .85em;
  border: 1px solid var(--line-strong);
  border-radius: var(--r-pill);
  background: rgba(11, 15, 14, .5);
  color: var(--moss);
  font-size: .78rem;
  font-weight: 700;
  letter-spacing: .05em;
}

.tag--flare { background: var(--flare); border-color: transparent; color: #1A0A06; }
.tag--blue { background: var(--blue); border-color: transparent; color: #04141F; }
.tag--amber { background: var(--amber); border-color: transparent; color: #241700; }

.slant {
  display: inline-block;
  padding: .35em 1.15em .35em .9em;
  background: var(--flare);
  color: #1A0602;
  font-family: var(--font-mono);
  font-weight: 800;
  font-size: .78rem;
  letter-spacing: .08em;
  clip-path: polygon(0 0, 100% 0, 92% 100%, 0 100%);
}

.slant--blue { background: var(--blue); color: #04141F; }
.slant--amber { background: var(--amber); color: #241700; }

/* ---------- 展签 ---------- */
.exhibit {
  display: inline-flex;
  flex-direction: column;
  gap: .15rem;
  padding-left: .85rem;
  border-left: 3px solid var(--flare);
}

.exhibit__no {
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--moss);
}

.exhibit__label { font-weight: 700; font-size: .95rem; color: var(--paper); }

/* ---------- 记分牌 ---------- */
.score {
  display: inline-flex;
  align-items: baseline;
  gap: .35rem;
  font-family: var(--font-mono);
  font-weight: 800;
  font-size: clamp(2rem, 5vw, 3.2rem);
  line-height: 1;
  letter-spacing: -.03em;
  color: var(--paper);
  font-variant-numeric: tabular-nums;
}

.score__sep { color: var(--flare); }
.score__unit { font-size: .9rem; font-weight: 600; letter-spacing: .1em; color: var(--moss); }

/* ---------- 面板 ---------- */
.panel {
  position: relative;
  padding: clamp(20px, 3vw, 34px);
  border: 1px solid var(--line);
  border-radius: var(--r-xl);
  background: linear-gradient(180deg, rgba(18, 59, 46, .82), rgba(14, 42, 34, .94));
  box-shadow: var(--shadow);
}

.panel--flat { background: var(--ink-2); box-shadow: none; }

.panel--blue {
  border-color: rgba(45, 156, 255, .38);
  background: linear-gradient(180deg, rgba(14, 42, 58, .8), rgba(9, 26, 38, .95));
}

.panel--flare {
  border-color: rgba(255, 77, 46, .45);
  background: linear-gradient(180deg, rgba(58, 21, 14, .72), rgba(20, 12, 10, .95));
}

.panel__head {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: .8rem;
  margin-bottom: 1rem;
}

.panel__title {
  font-family: var(--font-head);
  font-size: clamp(1.05rem, 1.8vw, 1.35rem);
  letter-spacing: -.01em;
}

/* ---------- 档案索引列表 ---------- */
.index-list { display: grid; }

.index-list__item {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  gap: .4rem 1rem;
  align-items: baseline;
  padding: .95rem .3rem;
  border-bottom: 1px dashed var(--line);
  transition: background-color var(--dur) var(--ease);
}

.index-list__item:hover { background: rgba(18, 59, 46, .5); }

.index-list__no {
  font-family: var(--font-mono);
  font-size: .8rem;
  color: var(--flare);
}

.index-list__title { font-weight: 700; color: var(--paper); }

.index-list__meta {
  font-family: var(--font-mono);
  font-size: .78rem;
  color: var(--moss);
  white-space: nowrap;
}

/* ---------- 抽屉式折叠组 ---------- */
.drawer {
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  background: rgba(14, 42, 34, .55);
  overflow: hidden;
}

.drawer + .drawer { margin-top: .75rem; }

.drawer__head { margin: 0; }

.drawer__btn {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  width: 100%;
  padding: 1rem 1.15rem;
  border: 0;
  background: none;
  color: var(--paper);
  font: inherit;
  font-weight: 700;
  text-align: left;
  cursor: pointer;
  transition: background-color var(--dur) var(--ease), color var(--dur) var(--ease);
}

.drawer__btn:hover { background: rgba(18, 59, 46, .9); color: var(--flare); }

.drawer__sign {
  position: relative;
  flex: none;
  width: 22px;
  height: 22px;
  border: 1px solid var(--line-strong);
  border-radius: 50%;
}

.drawer__sign::before,
.drawer__sign::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  width: 9px;
  height: 2px;
  background: var(--flare);
  transform: translate(-50%, -50%);
}

.drawer__sign::after {
  transform: translate(-50%, -50%) rotate(90deg);
  transition: transform var(--dur) var(--ease);
}

.drawer[data-open] .drawer__sign::after { transform: translate(-50%, -50%) rotate(0deg); }

.drawer__panel {
  display: grid;
  grid-template-rows: 0fr;
  visibility: hidden;
  transition: grid-template-rows var(--dur) var(--ease),
              visibility 0s linear var(--dur);
}

.drawer[data-open] .drawer__panel {
  grid-template-rows: 1fr;
  visibility: visible;
  transition: grid-template-rows var(--dur) var(--ease), visibility 0s;
}

.drawer__body {
  overflow: hidden;
  min-height: 0;
  padding: 0 1.15rem 1.15rem;
  color: #CFDCD6;
}

/* ---------- 网格 ---------- */
.grid { display: grid; gap: clamp(16px, 2.4vw, 28px); }

.grid--2 { grid-template-columns: repeat(auto-fit, minmax(min(100%, 300px), 1fr)); }
.grid--3 { grid-template-columns: repeat(auto-fit, minmax(min(100%, 250px), 1fr)); }
.grid--asym { grid-template-columns: minmax(0, 1.4fr) minmax(0, 1fr); }

@media (max-width: 820px) {
  .grid--asym { grid-template-columns: minmax(0, 1fr); }
}

/* ---------- 横向主题带与滑动轨道 ---------- */
.band {
  border-block: 1px solid var(--line);
  border-radius: var(--r-xl);
  background: linear-gradient(90deg, rgba(18, 59, 46, .85), rgba(11, 15, 14, .6));
  padding: clamp(20px, 3vw, 34px);
}

.band--blue {
  border-color: rgba(45, 156, 255, .3);
  background: linear-gradient(90deg, rgba(14, 42, 58, .85), rgba(11, 15, 14, .6));
}

.rail {
  display: flex;
  gap: clamp(12px, 2vw, 20px);
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  padding-bottom: .8rem;
  scrollbar-color: var(--flare) rgba(138, 163, 154, .18);
}

.rail > * {
  flex: 0 0 clamp(230px, 62%, 330px);
  scroll-snap-align: start;
}

.rail::-webkit-scrollbar { height: 6px; }
.rail::-webkit-scrollbar-track { background: rgba(138, 163, 154, .16); border-radius: 99px; }
.rail::-webkit-scrollbar-thumb { background: var(--flare); border-radius: 99px; }

/* ---------- 图版容器 ---------- */
.media-frame {
  position: relative;
  display: block;
  overflow: hidden;
  aspect-ratio: 16 / 10;
  border: 1px solid var(--line);
  border-radius: var(--r-lg);
  background-color: var(--ink-2);
  background-image:
    radial-gradient(120% 90% at 18% 0%, rgba(45, 156, 255, .22), transparent 62%),
    radial-gradient(100% 80% at 86% 100%, rgba(255, 77, 46, .24), transparent 60%),
    linear-gradient(160deg, var(--ink-3), var(--ink-2));
}

.media-frame img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.media-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image: repeating-linear-gradient(115deg, rgba(244, 247, 245, .05) 0 1px, transparent 1px 12px);
}

.media-frame--tall { aspect-ratio: 4 / 5; }
.media-frame--wide { aspect-ratio: 21 / 9; }

.media-frame__cap {
  position: absolute;
  left: 0;
  bottom: 0;
  z-index: 2;
  padding: .55em .95em;
  border-top-right-radius: var(--r-md);
  background: rgba(11, 15, 14, .78);
  color: var(--paper);
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .06em;
}

/* ---------- 面包屑 ---------- */
.crumbs { padding-block: .9rem; }

.crumbs__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: .4rem .7rem;
  font-family: var(--font-mono);
  font-size: .76rem;
  letter-spacing: .06em;
  color: var(--moss);
}

.crumbs__item { display: flex; align-items: center; gap: .7rem; }

.crumbs__item + .crumbs__item::before {
  content: "/";
  color: var(--line-strong);
}

.crumbs__link { color: var(--moss); }
.crumbs__link:hover { color: var(--ice); }

/* ==========================================================================
   头部
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 80;
  border-bottom: 1px solid var(--line);
  background: linear-gradient(180deg, rgba(11, 15, 14, .97), rgba(11, 15, 14, .87));
  backdrop-filter: blur(14px) saturate(1.2);
  -webkit-backdrop-filter: blur(14px) saturate(1.2);
}

.header-shell { position: relative; }

.masthead {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: clamp(12px, 2vw, 28px);
  padding-block: clamp(12px, 2vw, 18px);
}

.header-meta {
  margin: 0;
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--moss);
}

.header-meta .mono { color: var(--flare); }

.masthead__brand {
  display: inline-flex;
  align-items: center;
  gap: .7rem;
  justify-self: center;
  color: var(--paper);
  text-decoration: none;
}

.brand-mark {
  display: inline-grid;
  place-items: center;
  width: 44px;
  height: 44px;
  border-radius: 16px 16px 16px 6px;
  background: linear-gradient(150deg, var(--flare), var(--flare-soft));
  color: #170604;
  font-family: var(--font-mono);
  font-weight: 800;
  font-size: .92rem;
  letter-spacing: -.04em;
  box-shadow: 0 12px 26px -14px rgba(255, 77, 46, .9);
}

.brand-mark--sm {
  width: 34px;
  height: 34px;
  border-radius: 12px 12px 12px 4px;
  font-size: .76rem;
}

.wordmark {
  display: flex;
  flex-direction: column;
  line-height: 1.12;
}

.wordmark__name {
  font-family: var(--font-head);
  font-weight: 900;
  font-size: clamp(1.02rem, 1.5vw, 1.32rem);
  letter-spacing: .01em;
  color: var(--paper);
}

.wordmark__tag {
  font-family: var(--font-mono);
  font-size: .66rem;
  letter-spacing: .28em;
  color: var(--moss);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: .6rem;
  justify-self: end;
}

.header-cta {
  display: inline-flex;
  align-items: center;
  padding: .62em 1.15em;
  border-radius: var(--r-pill);
  background: var(--flare);
  color: #170604;
  font-weight: 800;
  font-size: .86rem;
  letter-spacing: .02em;
  white-space: nowrap;
  transition: transform var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.header-cta:hover {
  background: var(--flare-soft);
  color: #170604;
  transform: translateY(-2px);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: .5rem;
  padding: .58em .95em;
  border: 1px solid var(--line-strong);
  border-radius: var(--r-pill);
  background: rgba(18, 59, 46, .85);
  color: var(--paper);
  font-weight: 700;
  font-size: .84rem;
  cursor: pointer;
  transition: border-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

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

.nav-toggle__bars {
  position: relative;
  display: block;
  width: 18px;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
}

.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  width: 18px;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  transition: transform var(--dur) var(--ease);
}

.nav-toggle__bars::before { top: -6px; }
.nav-toggle__bars::after { top: 6px; }

.nav-toggle[aria-expanded="true"] .nav-toggle__bars { background: transparent; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars::before { transform: translateY(6px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars::after { transform: translateY(-6px) rotate(-45deg); }

.site-nav { border-top: 1px solid var(--line); }
.site-nav__inner { display: block; }

.site-nav__list {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: clamp(.2rem, 1.1vw, .85rem);
  padding: .4rem 0 .55rem;
}

.site-nav__link {
  display: inline-block;
  padding: .55em .95em;
  border-radius: var(--r-pill);
  color: #C7D5CF;
  font-weight: 600;
  font-size: .94rem;
  transition: color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.site-nav__link:hover {
  color: var(--paper);
  background: rgba(18, 59, 46, .9);
}

.site-nav__link[aria-current="page"] {
  background: var(--flare);
  color: #170604;
  font-weight: 800;
}

.site-nav__link[aria-current="page"]:hover { background: var(--flare-soft); color: #170604; }

.header-progress {
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 2px;
  transform: scaleX(0);
  transform-origin: left center;
  background: linear-gradient(90deg, var(--flare), var(--flare-soft) 55%, var(--amber));
  transition: transform .12s linear;
}

/* ==========================================================================
   页脚
   ========================================================================== */
.site-footer {
  position: relative;
  margin-top: clamp(50px, 8vw, 110px);
  border-top: 1px solid var(--line);
  background: linear-gradient(180deg, rgba(14, 42, 34, .55), rgba(7, 17, 13, .98));
}

.site-footer::before {
  content: "";
  position: absolute;
  top: -1px;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--flare), var(--flare-soft) 35%, var(--blue) 78%, var(--ice));
}

.footer-grid {
  display: grid;
  grid-template-columns:
    minmax(240px, 1.5fr)
    minmax(130px, .7fr)
    minmax(130px, .7fr)
    minmax(220px, 1.1fr);
  gap: clamp(22px, 3.5vw, 46px);
  padding: clamp(38px, 6vw, 72px) 0 clamp(26px, 4vw, 44px);
}

.footer-brand {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 1rem;
}

.footer-brand__row {
  display: flex;
  align-items: center;
  gap: .7rem;
}

.footer-desc {
  max-width: 34ch;
  color: var(--moss);
  font-size: .95rem;
  line-height: 1.75;
}

.footer-title {
  margin-bottom: .9rem;
  font-family: var(--font-mono);
  font-size: .72rem;
  font-weight: 700;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--ice);
}

.footer-links { display: grid; gap: .5rem; }

.footer-link {
  width: fit-content;
  padding-bottom: 2px;
  border-bottom: 1px solid transparent;
  color: #C6D4CE;
  font-size: .94rem;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.footer-link:hover {
  color: var(--flare);
  border-color: var(--flare);
}

.footer-contact {
  display: grid;
  gap: .7rem;
  font-style: normal;
}

.footer-contact__row { display: grid; gap: .12rem; }

.footer-contact__label {
  font-family: var(--font-mono);
  font-size: .68rem;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--moss);
}

.footer-contact__value {
  color: #D9E4DF;
  font-size: .95rem;
  word-break: break-word;
}

.footer-contact__note {
  max-width: 34ch;
  color: var(--moss);
  font-size: .82rem;
  line-height: 1.75;
}

.footer-base {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: .6rem 1.6rem;
  padding: clamp(16px, 2.5vw, 24px) 0 clamp(22px, 3vw, 32px);
  border-top: 1px solid var(--line);
  color: var(--moss);
  font-size: .82rem;
}

.footer-base__copy,
.footer-base__icp { margin: 0; }

.footer-base__copy .mono { color: var(--paper); }

/* ---------- 返回顶部 ---------- */
.backtop {
  position: fixed;
  right: clamp(14px, 3vw, 28px);
  bottom: clamp(14px, 3vw, 28px);
  z-index: 90;
  display: inline-flex;
  align-items: center;
  gap: .45rem;
  padding: .7em 1.1em;
  border: 1px solid var(--line-strong);
  border-radius: var(--r-pill);
  background: rgba(11, 15, 14, .92);
  color: var(--paper);
  font-weight: 700;
  font-size: .82rem;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: opacity var(--dur) var(--ease),
              transform var(--dur) var(--ease),
              visibility var(--dur) var(--ease),
              border-color var(--dur) var(--ease),
              color var(--dur) var(--ease);
}

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

.backtop:hover {
  border-color: var(--flare);
  color: var(--flare);
}

/* ==========================================================================
   响应式
   ========================================================================== */
@media (max-width: 980px) {
  .footer-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 880px) {
  .header-meta { display: none; }

  .masthead {
    grid-template-columns: auto 1fr auto;
    padding-block: 10px;
  }

  .masthead__brand { justify-self: start; }
  .wordmark__tag { display: none; }

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

  .site-nav {
    display: grid;
    grid-template-rows: 0fr;
    border-top: 0;
    transition: grid-template-rows var(--dur) var(--ease);
  }

  .site-nav[data-open] { grid-template-rows: 1fr; }

  .site-nav__inner {
    overflow: hidden;
    min-height: 0;
  }

  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
    padding: 0 0 14px;
    border-top: 1px solid var(--line);
  }

  .site-nav__link {
    display: block;
    padding: .85em 1em;
    border-radius: var(--r-md);
    font-size: 1rem;
  }

  .site-nav__link[aria-current="page"] { border-radius: var(--r-md); }

  #main-content { scroll-margin-top: 110px; }
}

@media (max-width: 560px) {
  .footer-grid { grid-template-columns: 1fr; }

  .header-cta {
    padding: .55em .9em;
    font-size: .78rem;
  }

  .brand-mark { width: 38px; height: 38px; border-radius: 14px 14px 14px 5px; font-size: .82rem; }

  .footer-base { flex-direction: column; align-items: flex-start; }

  .backtop { font-size: .76rem; }
}

/* ---------- 动效偏好 ---------- */
@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;
  }
}