/* ==========================================================================
   77棋牌主站 / 乐动体育 · 共享站点样式
   文件：/assets/site.css
   负责：reset、令牌、中文排版、页头、页脚、通用组件、响应式、动效偏好
   ========================================================================== */

/* ---------- 01. 设计令牌 ---------- */
:root {
  --ink-900: #07120E;
  --ink-800: #0B241C;
  --ink-700: #123328;
  --line: #1E4A3A;

  --lime: #C6FF4A;
  --lime-soft: rgba(198, 255, 74, .10);
  --lime-line: rgba(198, 255, 74, .32);
  --lime-ink: #06231A;

  --amber: #F5A623;
  --amber-line: rgba(245, 166, 35, .40);

  --paper: #F4F7F2;
  --muted: #8FA89D;

  --font-display: "Noto Serif SC", "Source Han Serif SC", "Songti SC", Georgia, "Times New Roman", serif;
  --font-body: Inter, "Helvetica Neue", -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;

  --shell: 1240px;
  --gutter: clamp(18px, 4vw, 56px);
  --header-h: 74px;

  --cut-sm: polygon(0 0, calc(100% - 12px) 0, 100% 12px, 100% 100%, 0 100%);
  --cut-md: polygon(0 0, calc(100% - 20px) 0, 100% 20px, 100% 100%, 20px 100%, 0 calc(100% - 20px));

  --ease: cubic-bezier(.22, .61, .36, 1);
  --dur: .26s;
}

@media (max-width: 1080px) {
  :root { --header-h: 66px; }
}
@media (max-width: 560px) {
  :root { --header-h: 60px; }
}

/* ---------- 02. Reset ---------- */
*,
*::before,
*::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  background-color: var(--ink-800);
  background-image:
    radial-gradient(120% 66% at 84% -14%, rgba(198, 255, 74, .075), transparent 62%),
    radial-gradient(96% 60% at -6% 104%, rgba(245, 166, 35, .05), transparent 58%),
    repeating-linear-gradient(0deg, rgba(244, 247, 242, .016) 0 1px, transparent 1px 3px);
  background-attachment: fixed;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font-body);
  font-size: 16px;
  font-weight: 400;
  line-height: 1.75;
  color: var(--paper);
  background-color: transparent;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img, svg, video { max-width: 100%; display: block; }
button, input, select, textarea { font: inherit; color: inherit; }
button { background: none; border: 0; cursor: pointer; }
ul, ol { margin: 0; padding: 0; list-style: none; }
table { border-collapse: collapse; width: 100%; }

h1, h2, h3, h4, h5 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.25;
  letter-spacing: .015em;
  margin: 0 0 .55em;
}
h1 { font-size: clamp(1.95rem, 4.4vw, 3.4rem); letter-spacing: .03em; }
h2 { font-size: clamp(1.45rem, 2.5vw, 2.15rem); }
h3 { font-size: clamp(1.1rem, 1.7vw, 1.4rem); }
h4 { font-size: 1rem; font-family: var(--font-body); font-weight: 600; letter-spacing: .02em; }

p { margin: 0 0 1.05em; }
p:last-child { margin-bottom: 0; }

a { color: var(--lime); text-decoration: none; transition: color var(--dur) var(--ease); }
a:hover { color: #E4FF9E; }
strong, b { font-weight: 600; color: var(--paper); }

hr { border: 0; border-top: 1px solid var(--line); margin: clamp(28px, 4vw, 48px) 0; }

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

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

[id] { scroll-margin-top: calc(var(--header-h) + 20px); }

/* ---------- 03. 布局与容器 ---------- */
.shell {
  width: min(100% - (var(--gutter) * 2), var(--shell));
  margin-inline: auto;
}
.shell--wide {
  width: min(100% - (var(--gutter) * 2), 1480px);
}

.section { padding-block: clamp(48px, 7vw, 96px); }
.section--flush { padding-block: 0; }

.section-head {
  display: grid;
  gap: 8px;
  max-width: 70ch;
  margin-bottom: clamp(20px, 3vw, 32px);
}
.section-head h2 { margin: 0; }
.section-head p { margin: 0; color: var(--muted); }

.eyebrow {
  font-family: var(--font-mono);
  font-size: .6875rem;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--muted);
}

.slash {
  height: 1px;
  border: 0;
  background: linear-gradient(90deg, var(--line) 0%, rgba(30, 74, 58, 0) 80%);
  margin: clamp(24px, 3.4vw, 44px) 0;
}

.visually-hidden {
  position: absolute !important;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

/* ---------- 04. 网格 ---------- */
.grid { display: grid; gap: clamp(16px, 2.4vw, 28px); }
.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.grid--split { grid-template-columns: minmax(200px, 268px) minmax(0, 1fr); }
.grid--wide-left { grid-template-columns: minmax(0, 1fr) minmax(200px, 300px); }

@media (max-width: 1040px) {
  .grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid--3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid--split,
  .grid--wide-left { grid-template-columns: minmax(0, 1fr); }
}
@media (max-width: 640px) {
  .grid--2,
  .grid--3,
  .grid--4 { grid-template-columns: minmax(0, 1fr); }
}

/* ---------- 05. 正文 ---------- */
.prose {
  max-width: 66ch;
  color: rgba(244, 247, 242, .88);
}
.prose h2 { margin-top: 1.6em; }
.prose h3 { margin-top: 1.4em; }
.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: .4em; }
.prose a { border-bottom: 1px solid var(--lime-line); }
.prose a:hover { border-bottom-color: var(--lime); }

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

/* ---------- 06. 面板 / 卡片 ---------- */
.panel {
  position: relative;
  background: var(--ink-700);
  border: 1px solid var(--line);
  clip-path: var(--cut-md);
  padding: clamp(18px, 2.6vw, 30px);
}
.panel--flat {
  clip-path: none;
  background: transparent;
}
.panel--accent {
  border-color: var(--lime-line);
  background:
    linear-gradient(180deg, var(--lime-soft), rgba(198, 255, 74, 0) 70%),
    var(--ink-700);
}
.panel--amber { border-color: var(--amber-line); }

.panel__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 14px;
  margin-bottom: 14px;
}
.panel__title {
  margin: 0;
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: .02em;
}
.panel__meta {
  font-family: var(--font-mono);
  font-size: .6875rem;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--muted);
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  font-family: var(--font-mono);
  font-size: .6875rem;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--lime);
  background: var(--lime-soft);
  border: 1px solid var(--lime-line);
}

.metric { display: grid; gap: 4px; }
.metric__value {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(1.5rem, 2.8vw, 2.1rem);
  font-weight: 600;
  line-height: 1.1;
  letter-spacing: -.01em;
  color: var(--lime);
}
.metric__value--amber { color: var(--amber); }
.metric__unit {
  font-size: .6em;
  color: var(--muted);
  margin-left: 2px;
}
.metric__label {
  font-size: .75rem;
  letter-spacing: .04em;
  color: var(--muted);
}

.note {
  font-size: .8125rem;
  line-height: 1.7;
  color: var(--muted);
  border-left: 2px solid var(--line);
  padding-left: 14px;
}
.note--lime { border-left-color: var(--lime); }

/* ---------- 07. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 13px 24px;
  font-family: inherit;
  font-size: .9375rem;
  font-weight: 600;
  letter-spacing: .02em;
  line-height: 1.3;
  color: var(--paper);
  background: transparent;
  border: 1px solid var(--line);
  clip-path: var(--cut-sm);
  transition: background var(--dur) var(--ease), color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.btn:hover {
  color: var(--lime);
  border-color: var(--lime);
  background: var(--lime-soft);
}
.btn--lime {
  color: var(--lime-ink);
  background: var(--lime);
  border-color: var(--lime);
}
.btn--lime:hover {
  color: var(--lime-ink);
  background: #D7FF74;
  border-color: #D7FF74;
}
.btn--ghost {
  color: var(--muted);
  border-color: var(--line);
}
.btn--ghost:hover {
  color: var(--lime);
  border-color: var(--lime-line);
  background: transparent;
}

/* ---------- 08. 面包屑 / 页内章节导航 ---------- */
.breadcrumb {
  font-family: var(--font-mono);
  font-size: .75rem;
  letter-spacing: .06em;
  color: var(--muted);
}
.breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.breadcrumb li + li::before {
  content: "/";
  margin-right: 8px;
  color: var(--line);
}
.breadcrumb a { color: var(--muted); }
.breadcrumb a:hover { color: var(--lime); }
.breadcrumb [aria-current="page"] { color: var(--paper); }

.anchor-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 18px;
  font-family: var(--font-mono);
  font-size: .75rem;
  letter-spacing: .08em;
}
.anchor-nav a {
  color: var(--muted);
  padding-bottom: 3px;
  border-bottom: 1px solid transparent;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.anchor-nav a:hover { color: var(--lime); }
.anchor-nav a[aria-current] {
  color: var(--lime);
  border-bottom-color: var(--lime);
}

/* ---------- 09. 图片容器 ---------- */
.figure {
  position: relative;
  margin: 0;
  overflow: hidden;
  background: var(--ink-700);
  border: 1px solid var(--line);
  clip-path: var(--cut-md);
}
.figure__media {
  position: relative;
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background:
    linear-gradient(135deg, rgba(198, 255, 74, .10), rgba(198, 255, 74, 0) 55%),
    linear-gradient(180deg, var(--ink-700), #0E2A21);
}
.figure__media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: saturate(.70) contrast(1.06) brightness(.92);
}
.figure__media::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    linear-gradient(115deg, rgba(198, 255, 74, .14), rgba(198, 255, 74, 0) 42%),
    linear-gradient(0deg, rgba(7, 18, 14, .55), rgba(7, 18, 14, 0) 65%);
}
.figure__caption {
  display: block;
  padding: 10px 2px 0;
  font-family: var(--font-mono);
  font-size: .75rem;
  letter-spacing: .02em;
  color: var(--muted);
}

.figure--wide .figure__media { aspect-ratio: 21 / 9; }
.figure--tall .figure__media { aspect-ratio: 3 / 4; }
.figure--square .figure__media { aspect-ratio: 1 / 1; }
.figure--auto .figure__media { aspect-ratio: auto; }

/* 占位纹样：球场中圈与十字战术线 */
.figure--placeholder .figure__media::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    linear-gradient(90deg, transparent 49.7%, rgba(198, 255, 74, .18) 49.7% 50.3%, transparent 50.3%),
    linear-gradient(0deg, transparent 49.7%, rgba(198, 255, 74, .18) 49.7% 50.3%, transparent 50.3%),
    radial-gradient(circle at 50% 50%, rgba(198, 255, 74, 0) 0 56px, rgba(198, 255, 74, .22) 56px 57px, rgba(198, 255, 74, 0) 57px);
}

/* ---------- 10. 展开式口径旁注 ---------- */
.disclose {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 5px 0;
  font-family: var(--font-mono);
  font-size: .6875rem;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--muted);
  border-bottom: 1px dashed var(--line);
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.disclose::before {
  content: "\25CF";
  font-size: .55em;
  line-height: 1;
  color: var(--line);
  transition: color var(--dur) var(--ease);
}
.disclose:hover {
  color: var(--lime);
  border-bottom-color: var(--lime-line);
}
.disclose[aria-expanded="true"] {
  color: var(--lime);
  border-bottom-color: var(--lime);
}
.disclose[aria-expanded="true"]::before { color: var(--lime); }

.disclose__panel {
  display: none;
  margin-top: 10px;
  padding-left: 14px;
  border-left: 2px solid var(--line);
  font-size: .8125rem;
  line-height: 1.7;
  color: var(--muted);
}
.disclose__panel[data-open] { display: block; }

/* ---------- 11. 页头 ---------- */
.skip-link {
  position: absolute;
  left: var(--gutter);
  top: -120px;
  z-index: 120;
  display: inline-block;
  padding: 11px 20px;
  font-size: .875rem;
  font-weight: 600;
  letter-spacing: .04em;
  color: var(--lime-ink);
  background: var(--lime);
  clip-path: var(--cut-sm);
  transition: top var(--dur) var(--ease);
}
.skip-link:hover { color: var(--lime-ink); }
.skip-link:focus { top: 14px; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 80;
  background: var(--ink-900);
  border-bottom: 1px solid var(--line);
}

.site-header__inner {
  width: min(100% - (var(--gutter) * 2), var(--shell));
  margin-inline: auto;
  min-height: var(--header-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: clamp(16px, 3vw, 44px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  flex: 0 0 auto;
  color: var(--paper);
}
.brand:hover { color: var(--paper); }

.brand__mark {
  position: relative;
  width: 34px;
  height: 34px;
  flex: 0 0 34px;
  background: var(--lime);
  clip-path: polygon(0 0, 100% 0, 100% 60%, 60% 100%, 0 100%);
}
.brand__mark::after {
  content: "";
  position: absolute;
  inset: 7px 8px;
  background: var(--ink-900);
  clip-path: polygon(50% 0, 100% 100%, 0 100%);
}

.brand__text { display: grid; gap: 2px; }
.brand__name {
  font-family: var(--font-display);
  font-size: 1.06rem;
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: .08em;
}
.brand__sub {
  font-family: var(--font-mono);
  font-size: .625rem;
  line-height: 1.2;
  letter-spacing: .14em;
  color: var(--muted);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 10px;
  padding: 9px 14px;
  color: var(--paper);
  border: 1px solid var(--line);
  clip-path: var(--cut-sm);
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease), background var(--dur) var(--ease);
}
.nav-toggle:hover,
.nav-toggle[aria-expanded="true"] {
  color: var(--lime);
  border-color: var(--lime);
  background: var(--lime-soft);
}
.nav-toggle__bars { display: grid; gap: 5px; width: 18px; }
.nav-toggle__bars i {
  display: block;
  height: 1.5px;
  background: currentColor;
  transition: transform var(--dur) var(--ease);
}
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:first-child {
  transform: translateY(3.25px) rotate(45deg);
}
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:last-child {
  transform: translateY(-3.25px) rotate(-45deg);
}
.nav-toggle__text {
  font-family: var(--font-mono);
  font-size: .8125rem;
  letter-spacing: .1em;
}

.site-nav__title,
.site-nav__foot { display: none; }

.site-nav__list {
  display: flex;
  align-items: center;
  gap: clamp(8px, 1.5vw, 24px);
}
.site-nav__item { display: block; }

.site-nav__link {
  position: relative;
  display: inline-flex;
  align-items: baseline;
  gap: 7px;
  padding: 8px 2px;
  font-size: .9375rem;
  line-height: 1.4;
  color: var(--paper);
}
.site-nav__label { white-space: nowrap; }
.site-nav__idx {
  font-family: var(--font-mono);
  font-size: .625rem;
  letter-spacing: .04em;
  color: var(--muted);
  transition: color var(--dur) var(--ease);
}
.site-nav__link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 1px;
  height: 1px;
  background: var(--lime);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform var(--dur) var(--ease);
}
.site-nav__link:hover { color: var(--paper); }
.site-nav__link:hover::after { transform: scaleX(1); }
.site-nav__link:hover .site-nav__idx { color: var(--lime); }
.site-nav__link[aria-current="page"] { color: var(--lime); }
.site-nav__link[aria-current="page"]::after { transform: scaleX(1); }
.site-nav__link[aria-current="page"] .site-nav__idx { color: var(--lime); }

.scroll-progress {
  position: absolute;
  left: 0;
  bottom: -1px;
  width: 100%;
  height: 2px;
  background: var(--lime);
  transform: scaleX(0);
  transform-origin: left center;
}

/* 移动端导航形态 */
@media (max-width: 1080px) {
  .nav-toggle { display: inline-flex; }

  .site-nav {
    position: fixed;
    top: var(--header-h);
    right: 0;
    bottom: 0;
    width: min(88vw, 360px);
    display: flex;
    flex-direction: column;
    gap: 18px;
    padding: 26px var(--gutter) 40px;
    background: var(--ink-900);
    border-left: 1px solid var(--line);
    overflow-y: auto;
    transform: translateX(100%);
    opacity: 0;
    visibility: hidden;
    transition:
      transform var(--dur) var(--ease),
      opacity var(--dur) var(--ease),
      visibility var(--dur) var(--ease);
  }
  .site-nav[data-open] {
    transform: translateX(0);
    opacity: 1;
    visibility: visible;
  }

  .site-nav__title {
    display: block;
    margin: 0;
    font-family: var(--font-mono);
    font-size: .625rem;
    letter-spacing: .2em;
    text-transform: uppercase;
    color: var(--muted);
  }
  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }
  .site-nav__item { border-bottom: 1px solid var(--line); }
  .site-nav__link {
    width: 100%;
    justify-content: flex-start;
    padding: 15px 0;
    font-size: 1.0625rem;
  }
  .site-nav__link::after { display: none; }
  .site-nav__link[aria-current="page"] {
    padding-left: 12px;
    border-left: 2px solid var(--lime);
  }
  .site-nav__foot {
    display: block;
    margin-top: auto;
    font-family: var(--font-mono);
    font-size: .6875rem;
    letter-spacing: .06em;
    color: var(--muted);
  }
}

@media (max-width: 560px) {
  .brand__sub { display: none; }
}

/* ---------- 12. 页脚 ---------- */
.site-footer {
  position: relative;
  margin-top: clamp(56px, 9vw, 120px);
  background: var(--ink-900);
  border-top: 1px solid var(--line);
}
.site-footer::before {
  content: "";
  position: absolute;
  top: -1px;
  left: 0;
  width: min(300px, 42vw);
  height: 2px;
  background: var(--lime);
}

.footer-grid {
  width: min(100% - (var(--gutter) * 2), var(--shell));
  margin-inline: auto;
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1.3fr;
  gap: clamp(24px, 3.4vw, 52px);
  padding-block: clamp(40px, 5.5vw, 72px) clamp(28px, 3.4vw, 44px);
}

.footer-brand {
  display: grid;
  gap: 12px;
  align-content: start;
}
.footer-brand__line {
  margin: 0;
  font-family: var(--font-display);
  font-size: 1rem;
  letter-spacing: .04em;
  color: var(--paper);
}
.footer-note {
  margin: 0;
  max-width: 34ch;
  font-size: .8125rem;
  line-height: 1.7;
  color: var(--muted);
}

.footer-nav__title {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: .625rem;
  font-weight: 500;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--lime);
}
.footer-nav__list { display: grid; gap: 9px; }
.footer-nav__list a {
  position: relative;
  display: inline-block;
  font-size: .9375rem;
  line-height: 1.5;
  color: var(--paper);
}
.footer-nav__list a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 1px;
  width: 100%;
  height: 1px;
  background: var(--lime);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform var(--dur) var(--ease);
}
.footer-nav__list a:hover { color: var(--lime); }
.footer-nav__list a:hover::after { transform: scaleX(1); }

.footer-contact__list {
  margin: 0;
  display: grid;
  gap: 4px;
}
.footer-contact__label {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: .625rem;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--muted);
}
.footer-contact__list dt:first-child { margin-top: 0; }
.footer-contact__value {
  margin: 0;
  font-size: .875rem;
  line-height: 1.6;
  color: var(--paper);
  overflow-wrap: anywhere;
}

.footer-base {
  width: min(100% - (var(--gutter) * 2), var(--shell));
  margin-inline: auto;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 8px 24px;
  padding-block: 18px clamp(22px, 3vw, 34px);
  border-top: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: .6875rem;
  letter-spacing: .06em;
  color: var(--muted);
}
.footer-base p { margin: 0; }

@media (max-width: 1040px) {
  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: 32px 28px;
  }
}
@media (max-width: 600px) {
  .footer-grid { grid-template-columns: 1fr; }
}

/* ---------- 13. 返回顶部 ---------- */
.to-top {
  position: fixed;
  right: clamp(14px, 2.6vw, 30px);
  bottom: clamp(14px, 2.6vw, 30px);
  z-index: 70;
  width: 48px;
  height: 48px;
  display: grid;
  place-items: center;
  font-size: 1rem;
  line-height: 1;
  color: var(--lime);
  background: var(--ink-700);
  border: 1px solid var(--line);
  clip-path: polygon(0 0, 100% 0, 100% 70%, 70% 100%, 0 100%);
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition:
    opacity var(--dur) var(--ease),
    transform var(--dur) var(--ease),
    visibility var(--dur) var(--ease),
    border-color var(--dur) var(--ease),
    background var(--dur) var(--ease);
}
.to-top[data-open] {
  opacity: 1;
  visibility: visible;
  transform: none;
}
.to-top:hover {
  border-color: var(--lime);
  background: var(--lime-soft);
}

/* ---------- 14. 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;
  }
}