/* =========================================================
   火博体育 · 通勤那一屏 — /assets/site.css
   线路隐喻：站点圆点 / 坐标索引 / 玻璃层 → 实色层
   ========================================================= */

/* 1. Reset ------------------------------------------------ */
*,
*::before,
*::after { box-sizing: border-box; }

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

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

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

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

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

button {
  background: none;
  border: 0;
  padding: 0;
  cursor: pointer;
}

a { color: inherit; text-decoration: none; }

table { border-collapse: collapse; width: 100%; }

:target { scroll-margin-top: 96px; }

/* 2. 变量 ------------------------------------------------ */
:root {
  --ink: #121417;
  --ink-2: #1E2329;
  --paper: #F4F1EA;
  --orange: #FF5A1F;
  --amber: #FFB27A;
  --blue: #2D7DFF;
  --mint: #57D6A3;
  --smoke: #727A84;
  --deep: #0B1220;
  --glass: rgba(255, 255, 255, 0.12);

  --line: rgba(244, 241, 234, 0.14);
  --line-soft: rgba(244, 241, 234, 0.08);
  --line-dark: rgba(18, 20, 23, 0.12);

  --font-head: "Archivo Black", "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-body: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;

  --shell: 1280px;
  --gutter: clamp(16px, 4vw, 40px);
  --header-h: 72px;
  --radius-s: 10px;
  --radius-m: 16px;
  --radius-l: 24px;
  --ease: cubic-bezier(.2, .7, .3, 1);
}

/* 3. 基础排版 -------------------------------------------- */
body {
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.7;
  color: var(--paper);
  background: var(--ink);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

h1, h2, h3, h4 {
  font-family: var(--font-head);
  font-weight: 800;
  line-height: 1.06;
  letter-spacing: -0.02em;
}

h1 { font-size: clamp(34px, 6vw, 76px); }
h2 { font-size: clamp(26px, 3.6vw, 48px); }
h3 { font-size: clamp(20px, 2.2vw, 28px); line-height: 1.2; letter-spacing: -0.01em; }

p { text-wrap: pretty; }

::selection {
  background: var(--orange);
  color: var(--ink);
}

:focus-visible {
  outline: 3px solid var(--amber);
  outline-offset: 3px;
  border-radius: 4px;
}

#main-content { scroll-margin-top: calc(var(--header-h) + 14px); }

/* 4. 通用工具类 ------------------------------------------ */
.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0;
}

.num {
  display: block;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: clamp(30px, 4.2vw, 46px);
  line-height: 1;
  color: var(--orange);
  font-variant-numeric: tabular-nums;
}

.muted { color: var(--smoke); }

.link {
  color: var(--amber);
  text-decoration: underline;
  text-underline-offset: 4px;
  text-decoration-thickness: 1px;
}
.link:hover { color: var(--orange); }

.container {
  width: 100%;
  max-width: var(--shell);
  margin-inline: auto;
  padding-inline: var(--gutter);
}
.container--narrow { max-width: 820px; }
.section { padding-block: clamp(48px, 7vw, 100px); }

.prose { max-width: 68ch; }
.prose p { margin-block-end: 1.1em; }
.prose p:last-child { margin-block-end: 0; }

.paper-layer { background: var(--paper); color: var(--ink); }
.paper-layer h1,
.paper-layer h2,
.paper-layer h3,
.paper-layer h4 { color: var(--ink); }
.paper-layer .muted { color: #5b636d; }

/* 5. 坐标标签 -------------------------------------------- */
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--amber);
}
.eyebrow::before {
  content: "";
  flex: 0 0 auto;
  width: 26px;
  height: 2px;
  background: var(--orange);
}
.paper-layer .eyebrow { color: #b8481a; }

.vertical-note {
  writing-mode: vertical-rl;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.26em;
  text-transform: uppercase;
  color: var(--smoke);
}

.rot-note {
  display: inline-block;
  transform: rotate(-90deg);
  transform-origin: left bottom;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--smoke);
  white-space: nowrap;
}

.section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 10px 18px;
  margin-block-end: clamp(20px, 3vw, 36px);
}

.route-rule {
  display: flex;
  align-items: center;
  gap: 12px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--smoke);
}
.route-rule::after {
  content: "";
  flex: 1 1 40px;
  height: 1px;
  background: linear-gradient(90deg, var(--orange), rgba(255, 90, 31, 0));
}

/* 6. 按钮 ------------------------------------------------ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 46px;
  padding: 11px 22px;
  border: 1px solid transparent;
  border-radius: 999px;
  font-family: var(--font-body);
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.01em;
  white-space: nowrap;
  transition:
    background-color .16s var(--ease),
    color .16s var(--ease),
    border-color .16s var(--ease),
    transform .16s var(--ease),
    box-shadow .16s var(--ease);
}
.btn--sm { min-height: 40px; padding: 8px 16px; font-size: 14px; }
.btn--solid {
  background: var(--orange);
  color: var(--ink);
  box-shadow: 0 8px 22px rgba(255, 90, 31, 0.28);
}
.btn--solid:hover {
  background: var(--amber);
  transform: translateY(-1px);
  box-shadow: 0 10px 26px rgba(255, 178, 122, 0.34);
}
.btn--ghost {
  background: var(--glass);
  color: var(--paper);
  border-color: rgba(244, 241, 234, 0.3);
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
}
.btn--ghost:hover {
  background: rgba(255, 255, 255, 0.22);
  border-color: var(--amber);
  color: #ffffff;
}
.btn--line {
  background: transparent;
  color: var(--paper);
  border-color: rgba(244, 241, 234, 0.34);
}
.btn--line:hover { border-color: var(--orange); color: var(--amber); }
.btn--block { width: 100%; }

.paper-layer .btn--line { color: var(--ink); border-color: rgba(18, 20, 23, 0.28); }
.paper-layer .btn--line:hover { border-color: var(--orange); color: #b8481a; }

/* 7. 标签与状态 ------------------------------------------ */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  border-radius: 999px;
  border: 1px solid rgba(255, 178, 122, 0.34);
  background: rgba(255, 178, 122, 0.14);
  color: var(--amber);
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.08em;
}
.tag--blue {
  border-color: rgba(45, 125, 255, 0.42);
  background: rgba(45, 125, 255, 0.16);
  color: #9cc0ff;
}
.tag--mint {
  border-color: rgba(87, 214, 163, 0.4);
  background: rgba(87, 214, 163, 0.14);
  color: var(--mint);
}

.dot {
  display: inline-block;
  flex: 0 0 auto;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--mint);
  box-shadow: 0 0 0 3px rgba(87, 214, 163, 0.18);
}
.dot--orange {
  background: var(--orange);
  box-shadow: 0 0 0 3px rgba(255, 90, 31, 0.2);
}

/* 8. 面包屑 ---------------------------------------------- */
.breadcrumb {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--smoke);
}
.breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}
.breadcrumb li { display: inline-flex; align-items: center; gap: 8px; }
.breadcrumb li + li::before { content: "/"; color: rgba(114, 122, 132, 0.6); }
.breadcrumb a { transition: color .16s var(--ease); }
.breadcrumb a:hover { color: var(--amber); }

/* 9. 布局与卡片 ------------------------------------------ */
.grid,
.grid--2,
.grid--3 {
  display: grid;
  gap: clamp(16px, 2.2vw, 28px);
  grid-template-columns: 1fr;
}

@media (min-width: 720px) {
  .grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid--3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (min-width: 1040px) {
  .grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

.card {
  position: relative;
  padding: clamp(18px, 2.4vw, 28px);
  border-radius: var(--radius-m);
  background: var(--ink-2);
  border: 1px solid var(--line-soft);
  transition: border-color .18s var(--ease), transform .18s var(--ease);
}
.card:hover { border-color: rgba(255, 178, 122, 0.4); }

.card--paper {
  background: var(--paper);
  color: var(--ink);
  border-color: var(--line-dark);
}
.card--paper h3 { color: var(--ink); }

.glass {
  background: var(--glass);
  border: 1px solid rgba(255, 255, 255, 0.18);
  border-radius: var(--radius-m);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
}

/* 10. 图片容器基础规则 ----------------------------------- */
.media-frame {
  position: relative;
  overflow: hidden;
  border-radius: var(--radius-m);
  border: 1px solid rgba(244, 241, 234, 0.14);
  background:
    radial-gradient(120% 90% at 12% 8%, rgba(45, 125, 255, 0.22), transparent 58%),
    radial-gradient(90% 80% at 88% 92%, rgba(255, 90, 31, 0.26), transparent 60%),
    linear-gradient(158deg, #1E2329 0%, #0B1220 72%);
  isolation: isolate;
}
.media-frame > img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.media-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image: repeating-linear-gradient(0deg, rgba(255, 255, 255, 0.045) 0 1px, transparent 1px 4px);
  mix-blend-mode: overlay;
}
.media-frame--square { aspect-ratio: 1 / 1; }
.media-frame--wide { aspect-ratio: 16 / 9; }
.media-frame--tall { aspect-ratio: 3 / 4; }
.media-frame--rail { aspect-ratio: 21 / 9; }

.media-frame__coord {
  position: absolute;
  left: 12px;
  bottom: 12px;
  z-index: 2;
  padding: 3px 8px;
  border-radius: 4px;
  background: rgba(11, 18, 32, 0.72);
  color: var(--amber);
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

/* 11. 头部 ----------------------------------------------- */
.site-header {
  position: fixed;
  inset-block-start: 0;
  inset-inline: 0;
  z-index: 100;
  color: var(--paper);
  background: linear-gradient(180deg, rgba(11, 18, 32, 0.86) 0%, rgba(11, 18, 32, 0.36) 62%, rgba(11, 18, 32, 0) 100%);
  transition: background-color .18s var(--ease), box-shadow .18s var(--ease);
}
.site-header.is-solid {
  background: var(--ink);
  box-shadow: 0 1px 0 var(--line), 0 14px 34px rgba(0, 0, 0, 0.42);
}

.skip-link {
  position: absolute;
  top: -90px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 300;
  padding: 12px 22px;
  border-radius: 0 0 12px 12px;
  background: var(--orange);
  color: var(--ink);
  font-size: 14px;
  font-weight: 800;
  transition: top .18s var(--ease);
}
.skip-link:focus { top: 0; }

.header-shell {
  display: flex;
  align-items: center;
  gap: clamp(12px, 2vw, 28px);
  width: 100%;
  max-width: var(--shell);
  min-height: var(--header-h);
  margin-inline: auto;
  padding: 14px var(--gutter);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  flex: 0 0 auto;
}
.brand-mark {
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border-radius: 11px;
  background: var(--orange);
  color: var(--ink);
  font-family: var(--font-head);
  font-size: 20px;
  line-height: 1;
  box-shadow: inset 0 0 0 1px rgba(18, 20, 23, 0.28);
}
.brand-text { display: flex; flex-direction: column; gap: 2px; }
.brand-line {
  font-family: var(--font-head);
  font-size: 15px;
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: 0.01em;
}
.brand-sub {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--smoke);
}

.site-nav { margin-inline-start: auto; }
.nav-route { display: flex; align-items: center; gap: clamp(4px, 1vw, 16px); }
.nav-stop { display: flex; }
.nav-stop a {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 9px 8px;
  font-size: 14px;
  font-weight: 500;
  color: rgba(244, 241, 234, 0.76);
  transition: color .16s var(--ease);
}
.nav-stop a::before {
  content: "";
  flex: 0 0 auto;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  border: 1.5px solid rgba(244, 241, 234, 0.42);
  background: transparent;
  transition: background-color .16s var(--ease), border-color .16s var(--ease), box-shadow .16s var(--ease);
}
.nav-stop a:hover { color: var(--paper); }
.nav-stop a:hover::before { border-color: var(--amber); }
.nav-stop a[aria-current="page"] { color: var(--paper); font-weight: 700; }
.nav-stop a[aria-current="page"]::before {
  background: var(--orange);
  border-color: var(--orange);
  box-shadow: 0 0 0 4px rgba(255, 90, 31, 0.18);
}

.header-actions { display: flex; align-items: center; gap: 10px; flex: 0 0 auto; }

.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  min-height: 42px;
  padding: 8px 14px;
  border-radius: 999px;
  border: 1px solid rgba(244, 241, 234, 0.28);
  background: var(--glass);
  color: var(--paper);
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
}
.nav-toggle-text { font-size: 13px; font-weight: 700; letter-spacing: 0.04em; }
.nav-toggle-icon { display: grid; gap: 4px; width: 16px; }
.nav-toggle-icon span {
  display: block;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  transition: transform .2s var(--ease), opacity .2s var(--ease);
}
.nav-toggle[aria-expanded="true"] .nav-toggle-icon span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle-icon span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle-icon span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }

.read-line {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 2px;
  background: rgba(244, 241, 234, 0.12);
}
.read-line > span {
  display: block;
  height: 100%;
  width: 0;
  background: linear-gradient(90deg, var(--orange), var(--amber));
}

@keyframes nav-drop {
  from { opacity: 0; transform: translateY(-8px); }
  to { opacity: 1; transform: none; }
}

@media (max-width: 960px) {
  .site-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    display: none;
    margin: 0;
    padding: 6px var(--gutter) 22px;
    background: var(--ink-2);
    border-block: 1px solid var(--line);
    max-height: calc(100vh - var(--header-h));
    overflow-y: auto;
    box-shadow: 0 22px 44px rgba(0, 0, 0, 0.5);
  }
  .site-nav[data-open="true"] {
    display: block;
    animation: nav-drop .22s var(--ease) both;
  }
  .nav-route { flex-direction: column; align-items: stretch; gap: 0; }
  .nav-stop a {
    padding: 15px 4px;
    font-size: 16px;
    border-bottom: 1px dashed rgba(244, 241, 234, 0.12);
  }
  .nav-stop:last-child a { border-bottom: 0; }
  .nav-toggle { display: inline-flex; }
  .header-actions .btn { display: none; }
  .brand-line { font-size: 14px; }
  .brand-sub { font-size: 9px; }
}

@media (min-width: 961px) {
  :root { --header-h: 76px; }
  .header-shell { padding-block: 16px; }
}

/* 12. 页脚 ----------------------------------------------- */
.site-footer {
  position: relative;
  overflow: hidden;
  background: var(--deep);
  color: var(--paper);
  border-block-start: 1px solid rgba(255, 90, 31, 0.42);
  padding-block: clamp(44px, 6vw, 84px) clamp(20px, 3vw, 32px);
}
.site-footer::before {
  content: "";
  position: absolute;
  inset-block-start: 0;
  inset-inline: 0;
  height: 1px;
  background: linear-gradient(90deg, var(--orange), rgba(255, 90, 31, 0) 62%);
}

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

.footer-top {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(28px, 4vw, 56px);
}
@media (min-width: 900px) {
  .footer-top { grid-template-columns: minmax(260px, 1fr) minmax(0, 1.35fr); }
}

.footer-brand { display: grid; gap: 16px; align-content: start; }
.brand--footer .brand-mark { background: var(--paper); color: var(--ink); }
.footer-summary {
  max-width: 34ch;
  font-size: 15px;
  line-height: 1.75;
  color: rgba(244, 241, 234, 0.82);
}
.footer-refresh {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  max-width: 40ch;
  font-size: 12.5px;
  line-height: 1.7;
  color: var(--smoke);
}
.footer-refresh .dot { margin-block-start: 8px; }

.footer-nav {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: clamp(20px, 3vw, 40px);
}
@media (min-width: 620px) {
  .footer-nav { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

.footer-group { display: grid; gap: 12px; align-content: start; }
.footer-title {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 700;
  line-height: 1.4;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--amber);
}
.footer-title::before {
  content: "";
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--orange);
}

.footer-list { display: grid; gap: 2px; }
.footer-list a {
  display: inline-flex;
  align-items: center;
  padding: 6px 0;
  font-size: 14.5px;
  color: rgba(244, 241, 234, 0.74);
  transition: color .16s var(--ease), transform .16s var(--ease);
}
.footer-list a::after {
  content: "→";
  margin-inline-start: 8px;
  color: var(--orange);
  opacity: 0;
  transform: translateX(-4px);
  transition: opacity .16s var(--ease), transform .16s var(--ease);
}
.footer-list a:hover { color: var(--paper); transform: translateX(2px); }
.footer-list a:hover::after { opacity: 1; transform: none; }

.footer-contact {
  display: grid;
  gap: 14px;
  margin-block-start: clamp(28px, 4vw, 48px);
  padding-block-start: clamp(20px, 3vw, 28px);
  border-block-start: 1px solid rgba(244, 241, 234, 0.1);
}

.contact-list { display: grid; grid-template-columns: 1fr; gap: 8px; }
@media (min-width: 760px) {
  .contact-list { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .contact-item--wide { grid-column: 1 / -1; }
}

.contact-item {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  padding: 10px 14px;
  border-radius: var(--radius-s);
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(244, 241, 234, 0.1);
}
.contact-key {
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--smoke);
}
.contact-value {
  font-family: var(--font-mono);
  font-size: 13.5px;
  line-height: 1.5;
  color: var(--paper);
  word-break: break-word;
}
.copy-btn {
  margin-inline-start: auto;
  padding: 3px 10px;
  border-radius: 999px;
  border: 1px solid rgba(255, 178, 122, 0.4);
  color: var(--amber);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.06em;
  transition: background-color .16s var(--ease), color .16s var(--ease), border-color .16s var(--ease);
}
.copy-btn:hover { background: var(--amber); color: var(--ink); border-color: var(--amber); }
.copy-btn.is-copied { background: var(--mint); border-color: var(--mint); color: var(--ink); }

.contact-note {
  max-width: 62ch;
  font-size: 12.5px;
  line-height: 1.7;
  color: var(--smoke);
}

.footer-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 20px;
  margin-block-start: clamp(28px, 4vw, 44px);
  padding-block-start: 16px;
  border-block-start: 1px solid rgba(244, 241, 234, 0.1);
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.06em;
  color: var(--smoke);
}
.footer-legal { color: var(--smoke); }
.footer-icp { color: rgba(244, 241, 234, 0.7); }
.footer-coord { letter-spacing: 0.16em; text-transform: uppercase; }

/* 13. 悬浮入口 ------------------------------------------- */
.thumb-cta {
  position: fixed;
  right: clamp(14px, 3vw, 28px);
  bottom: clamp(14px, 3vw, 26px);
  z-index: 90;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 46px;
  padding: 0 20px;
  border-radius: 999px;
  background: var(--orange);
  color: var(--ink);
  font-size: 14px;
  font-weight: 800;
  letter-spacing: 0.02em;
  box-shadow: 0 12px 26px rgba(255, 90, 31, 0.34);
  transition: background-color .16s var(--ease), transform .16s var(--ease);
}
.thumb-cta::before {
  content: "";
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: rgba(18, 20, 23, 0.7);
}
.thumb-cta:hover { background: var(--amber); transform: translateY(-2px); }

.to-top {
  position: fixed;
  right: clamp(14px, 3vw, 28px);
  bottom: calc(clamp(14px, 3vw, 26px) + 58px);
  z-index: 90;
  display: grid;
  place-items: center;
  width: 46px;
  height: 46px;
  border-radius: 50%;
  border: 1px solid rgba(244, 241, 234, 0.28);
  background: rgba(30, 35, 41, 0.92);
  color: var(--paper);
  font-size: 17px;
  line-height: 1;
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
  opacity: 0;
  pointer-events: none;
  transform: translateY(10px);
  transition: opacity .2s var(--ease), transform .2s var(--ease), background-color .2s var(--ease), color .2s var(--ease);
}
.to-top.is-visible { opacity: 1; pointer-events: auto; transform: none; }
.to-top:hover { background: var(--orange); border-color: var(--orange); color: var(--ink); }

/* 14. 滚动显现 ------------------------------------------- */
html.js-reveal [data-reveal] {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity .5s var(--ease), transform .55s var(--ease);
}
html.js-reveal [data-reveal].is-in {
  opacity: 1;
  transform: none;
}

/* 15. 减动效 --------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *,
  *::before,
  *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
    scroll-behavior: auto !important;
  }
  html.js-reveal [data-reveal] { opacity: 1; transform: none; }
  .footer-list a:hover { transform: none; }
  .thumb-cta:hover { transform: none; }
}