/* =========================================================
   site.css — 完美体育入口 / 城市看台框架外壳
   ========================================================= */

/* ---------- 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, figcaption, blockquote { margin: 0; padding: 0; }

ul, ol { list-style: none; }

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

button { font: inherit; color: inherit; }

a { color: inherit; }

/* ---------- 2. Tokens ---------- */
:root {
  --ink: #0B2A22;
  --ink-deep: #071C17;
  --concrete: #8E948C;
  --paper: #F2EBDD;
  --lime: #C8FF3D;
  --rust: #7A1F1F;
  --turf: #1E5B3A;
  --steel: #141716;
  --concrete-l: #D6D4CB;
  --white: #FFFFFF;

  --rail-w: 236px;
  --topbar-h: 62px;
  --thumbs-h: 62px;
  --pad-x: clamp(16px, 4vw, 52px);
  --maxw: 1280px;

  --line: rgba(242, 235, 221, 0.14);
  --line-2: rgba(242, 235, 221, 0.32);
  --line-ink: rgba(20, 23, 22, 0.16);
  --line-ink-2: rgba(20, 23, 22, 0.38);

  --font-sans: "Noto Sans SC", "Source Han Sans SC", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", system-ui, -apple-system,
    "Segoe UI", sans-serif;
  --font-mono: "IBM Plex Mono", "JetBrains Mono", SFMono-Regular, ui-monospace,
    "SF Mono", Menlo, Consolas, "Courier New", monospace;

  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

@media (max-width: 599px) {
  :root {
    --topbar-h: 56px;
    --thumbs-h: 58px;
  }
}

/* ---------- 3. 中文排版基线 ---------- */
body {
  min-height: 100vh;
  background-color: var(--ink);
  color: var(--paper);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.55;
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4 {
  font-weight: 900;
  line-height: 1.08;
  letter-spacing: -0.02em;
  text-wrap: balance;
}

p { text-wrap: pretty; }

h1 { font-size: clamp(40px, 7vw, 96px); }
h2 { font-size: clamp(28px, 4vw, 56px); }
h3 { font-size: clamp(20px, 2.2vw, 28px); }
h4 { font-size: 17px; letter-spacing: 0; }

p + p { margin-top: 1.2em; }

strong { font-weight: 800; }

/* ---------- 4. 焦点与可访问性 ---------- */
:focus-visible {
  outline: 2px solid var(--lime);
  outline-offset: 3px;
}

.skip-link {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 200;
  padding: 10px 18px;
  background: var(--lime);
  color: var(--steel);
  font-size: 14px;
  font-weight: 900;
  letter-spacing: 0.02em;
  text-decoration: none;
  border-radius: 2px;
  transform: translateY(-180%);
  transition: transform 0.18s var(--ease);
}

.skip-link:focus,
.skip-link:focus-visible { transform: translateY(0); }

#main-content { scroll-margin-top: calc(var(--topbar-h) + 18px); }

/* ---------- 5. 页面骨架偏移 ---------- */
@media (min-width: 960px) {
  body {
    padding-top: var(--topbar-h);
    padding-left: var(--rail-w);
  }
}

@media (max-width: 959px) {
  body {
    padding-top: var(--topbar-h);
    padding-bottom: var(--thumbs-h);
  }
}

body.is-locked { overflow: hidden; }

/* ---------- 6. 顶部状态横条 ---------- */
.site-header { position: relative; z-index: 60; }

.topbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--topbar-h);
  display: flex;
  align-items: center;
  gap: clamp(10px, 2vw, 22px);
  padding: 0 clamp(14px, 3vw, 26px);
  background: var(--ink-deep);
  border-bottom: 1px solid var(--line-2);
  z-index: 60;
}

.brand {
  display: flex;
  align-items: center;
  gap: 11px;
  flex: 0 0 auto;
  color: var(--paper);
  text-decoration: none;
}

.brand__mark {
  width: 22px;
  height: 22px;
  flex: 0 0 22px;
  border-left: 2px solid var(--lime);
  background-image:
    linear-gradient(var(--lime), var(--lime)),
    linear-gradient(var(--lime), var(--lime)),
    linear-gradient(var(--lime), var(--lime));
  background-repeat: no-repeat;
  background-position: 0 2px, 0 9px, 0 16px;
  background-size: 100% 3px, 72% 3px, 44% 3px;
}

.brand__text { display: block; min-width: 0; }

.brand__name {
  display: block;
  font-size: 17px;
  font-weight: 900;
  letter-spacing: 0.03em;
  line-height: 1.1;
}

.brand__sub {
  display: block;
  margin-top: 2px;
  font-family: var(--font-mono);
  font-size: 9px;
  line-height: 1.2;
  letter-spacing: 0.22em;
  color: var(--concrete);
}

.topbar__status {
  display: none;
  align-items: center;
  gap: 10px;
  margin-left: 4px;
  padding-left: 18px;
  border-left: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--concrete);
  white-space: nowrap;
}

@media (min-width: 720px) {
  .topbar__status { display: flex; }
}

.topbar__dot {
  width: 6px;
  height: 6px;
  flex: 0 0 6px;
  border-radius: 50%;
  background: var(--lime);
  box-shadow: 0 0 0 3px rgba(200, 255, 61, 0.14);
  animation: pulse 2.6s var(--ease) infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.35; }
}

.topbar__sep { opacity: 0.45; }

.topbar__actions {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 10px;
}

.topbar__cta { display: none; }

@media (min-width: 960px) {
  .topbar__cta { display: inline-flex; }
}

.topbar__progress {
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 2px;
  background: var(--lime);
  opacity: 0.92;
  transform: scaleX(0);
  transform-origin: 0 50%;
  pointer-events: none;
}

/* ---------- 7. 移动导航按钮 ---------- */
.nav-toggle {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 40px;
  padding: 8px 12px;
  background: transparent;
  color: var(--paper);
  border: 1px solid var(--line-2);
  border-radius: 2px;
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.04em;
  cursor: pointer;
  transition: background 0.16s var(--ease), color 0.16s var(--ease),
    border-color 0.16s var(--ease);
}

@media (min-width: 960px) {
  .nav-toggle { display: none; }
}

.nav-toggle__bars {
  display: block;
  width: 16px;
}

.nav-toggle__bars span {
  display: block;
  height: 2px;
  background: currentColor;
  transition: transform 0.2s var(--ease), opacity 0.2s var(--ease);
}

.nav-toggle__bars span + span { margin-top: 4px; }

[data-site-header][data-open] .nav-toggle {
  background: var(--lime);
  border-color: var(--lime);
  color: var(--steel);
}

[data-site-header][data-open] .nav-toggle__bars span:first-child {
  transform: translateY(3px) rotate(45deg);
}

[data-site-header][data-open] .nav-toggle__bars span:last-child {
  transform: translateY(-3px) rotate(-45deg);
}

/* ---------- 8. 左侧索引导轨 ---------- */
.rail {
  position: fixed;
  top: var(--topbar-h);
  left: 0;
  bottom: 0;
  width: var(--rail-w);
  display: flex;
  flex-direction: column;
  padding: 24px 16px 18px;
  background: var(--ink-deep);
  border-right: 1px solid var(--line-2);
  overflow-y: auto;
  z-index: 50;
}

.rail__label {
  padding-bottom: 12px;
  margin-bottom: 14px;
  border-bottom: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.24em;
  color: var(--concrete);
}

.rail__list {
  display: flex;
  flex-direction: column;
  gap: 2px;
  flex: 1 1 auto;
}

.rail__link {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 11px 10px 11px 12px;
  border-left: 2px solid transparent;
  color: var(--paper);
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.01em;
  text-decoration: none;
  transition: background 0.16s var(--ease), border-color 0.16s var(--ease),
    color 0.16s var(--ease);
}

.rail__num {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.1em;
  color: var(--concrete);
  transition: color 0.16s var(--ease);
}

.rail__text { display: block; }

.rail__link:hover {
  background: rgba(242, 235, 221, 0.06);
  border-left-color: var(--concrete);
}

.rail__link:hover .rail__num { color: var(--lime); }

.rail__link[aria-current="page"] {
  background: var(--lime);
  border-left-color: var(--lime);
  color: var(--steel);
}

.rail__link[aria-current="page"] .rail__num { color: var(--steel); }

.rail__foot {
  margin-top: auto;
  padding-top: 16px;
  border-top: 1px solid var(--line);
}

.rail__meta {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.14em;
  color: var(--concrete);
}

.rail__footlink {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-top: 10px;
  min-height: 36px;
  font-size: 13px;
  font-weight: 800;
  color: var(--lime);
  text-decoration: none;
  border-bottom: 1px solid rgba(200, 255, 61, 0.4);
  transition: color 0.16s var(--ease), border-color 0.16s var(--ease);
}

.rail__footlink:hover {
  color: var(--paper);
  border-color: var(--paper);
}

@media (max-width: 959px) {
  .rail {
    top: var(--topbar-h);
    left: 0;
    right: 0;
    bottom: var(--thumbs-h);
    width: auto;
    padding: 20px var(--pad-x) 28px;
    border-right: 0;
    border-bottom: 1px solid var(--line-2);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    pointer-events: none;
    transition: opacity 0.2s var(--ease), transform 0.2s var(--ease),
      visibility 0.2s linear;
    z-index: 58;
  }

  [data-site-header][data-open] .rail {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
    pointer-events: auto;
  }

  .rail__label { margin-bottom: 12px; }

  .rail__link {
    padding: 13px 12px 13px 14px;
    font-size: 17px;
  }

  .rail__foot { margin-top: 22px; }
}

/* ---------- 9. 移动端底部快捷入口 ---------- */
.thumb-nav { display: none; }

@media (max-width: 959px) {
  .thumb-nav {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1px;
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    height: var(--thumbs-h);
    background: var(--line-2);
    border-top: 1px solid var(--line-2);
    z-index: 65;
  }

  .thumb-nav__link {
    display: flex;
    flex-direction: column;
    justify-content: center;
    gap: 2px;
    padding: 0 18px;
    background: var(--ink-deep);
    color: var(--paper);
    text-decoration: none;
  }

  .thumb-nav__label {
    font-size: 15px;
    font-weight: 900;
    letter-spacing: 0.04em;
    line-height: 1.2;
  }

  .thumb-nav__hint {
    font-family: var(--font-mono);
    font-size: 9.5px;
    letter-spacing: 0.16em;
    color: var(--concrete);
    line-height: 1.2;
  }

  .thumb-nav__link--alt .thumb-nav__label { color: var(--lime); }
}

/* ---------- 10. 页脚 ---------- */
.site-footer {
  position: relative;
  padding: clamp(34px, 5vw, 66px) var(--pad-x) 0;
  background-color: var(--concrete);
  background-image:
    linear-gradient(to right, rgba(20, 23, 22, 0.08) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(20, 23, 22, 0.08) 1px, transparent 1px);
  background-size: 56px 100%, 100% 56px;
  border-top: 2px solid var(--steel);
  color: var(--steel);
}

.footer__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(24px, 3vw, 40px);
  width: 100%;
  max-width: var(--maxw);
  margin-inline: auto;
  padding-bottom: clamp(24px, 4vw, 46px);
}

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

@media (min-width: 1024px) {
  .footer__grid {
    grid-template-columns: 1.55fr 1fr 1fr 1.35fr;
    gap: clamp(24px, 3vw, 46px);
  }
}

.footer__brand { min-width: 0; }

.footer__name {
  font-size: clamp(22px, 2.6vw, 32px);
  font-weight: 900;
  letter-spacing: -0.02em;
  line-height: 1.1;
  color: var(--steel);
}

.footer__note {
  max-width: 34ch;
  margin-top: 12px;
  font-size: 13px;
  line-height: 1.62;
  color: rgba(20, 23, 22, 0.76);
}

.footer__stamp {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-top: 16px;
  padding: 6px 10px;
  border: 1px solid var(--line-ink-2);
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.12em;
}

.footer__stamp-key { opacity: 0.62; }

.footer__stamp-val { font-weight: 700; }

.footer__col { min-width: 0; }

.footer__title {
  padding-bottom: 10px;
  margin-bottom: 10px;
  border-bottom: 1px solid var(--line-ink-2);
  font-family: var(--font-mono);
  font-size: 10.5px;
  font-weight: 700;
  letter-spacing: 0.22em;
  line-height: 1.4;
  color: var(--steel);
}

.footer__list li + li { margin-top: 2px; }

.footer__link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 0;
  min-height: 32px;
  font-size: 14px;
  font-weight: 600;
  color: var(--steel);
  text-decoration: none;
  transition: color 0.16s var(--ease);
}

.footer__link::before {
  content: "";
  display: block;
  width: 0;
  height: 1px;
  background: currentColor;
  transition: width 0.18s var(--ease);
}

.footer__link:hover { color: var(--turf); }

.footer__link:hover::before { width: 12px; }

.contact-list { display: flex; flex-direction: column; }

.contact-list__item {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px 10px;
  padding: 9px 0;
  border-bottom: 1px dashed rgba(20, 23, 22, 0.26);
}

.contact-list__item:last-child { border-bottom: 0; }

.contact-list__key {
  flex: 0 0 34px;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.14em;
  color: rgba(20, 23, 22, 0.62);
}

.contact-list__val {
  flex: 1 1 auto;
  min-width: 0;
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: 0.02em;
  line-height: 1.5;
  word-break: break-word;
  color: var(--steel);
}

.copy {
  flex: 0 0 auto;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 26px;
  padding: 3px 9px;
  background: transparent;
  border: 1px solid rgba(20, 23, 22, 0.4);
  border-radius: 2px;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.1em;
  color: var(--steel);
  cursor: pointer;
  transition: background 0.16s var(--ease), color 0.16s var(--ease),
    border-color 0.16s var(--ease);
}

.copy:hover {
  background: var(--steel);
  border-color: var(--steel);
  color: var(--paper);
}

.copy[data-copied="true"] {
  background: var(--turf);
  border-color: var(--turf);
  color: var(--paper);
}

.footer__base {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 8px 24px;
  width: 100%;
  max-width: var(--maxw);
  margin-inline: auto;
  padding: 16px 0 22px;
  border-top: 1px solid rgba(20, 23, 22, 0.26);
}

.footer__legal {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  line-height: 1.6;
  color: rgba(20, 23, 22, 0.8);
}

/* ---------- 11. 回到顶部 ---------- */
.to-top {
  position: fixed;
  right: clamp(14px, 3vw, 28px);
  bottom: calc(var(--thumbs-h) + 14px);
  z-index: 70;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 44px;
  padding: 10px 14px;
  background: var(--ink-deep);
  border: 1px solid var(--line-2);
  border-radius: 2px;
  color: var(--paper);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity 0.2s var(--ease), transform 0.2s var(--ease),
    visibility 0.2s linear, background 0.16s var(--ease), color 0.16s var(--ease);
}

.to-top[data-visible="true"] {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.to-top:hover {
  background: var(--lime);
  border-color: var(--lime);
  color: var(--steel);
}

.to-top__arrow { font-size: 13px; line-height: 1; }

@media (min-width: 960px) {
  .to-top { bottom: 26px; }
}

/* ---------- 12. 通用布局与内容组件 ---------- */
.shell {
  width: 100%;
  max-width: var(--maxw);
  margin-inline: auto;
  padding-inline: var(--pad-x);
}

.section { padding-block: clamp(42px, 6vw, 88px); }

.section--tight { padding-block: clamp(26px, 3.5vw, 48px); }

.section--ink {
  background: var(--ink-deep);
  color: var(--paper);
}

.section--paper {
  background: var(--paper);
  color: var(--steel);
}

.section--paper a { color: inherit; }

.section-head {
  display: flex;
  flex-direction: column;
  gap: 14px;
  margin-bottom: clamp(22px, 3vw, 40px);
  max-width: 68ch;
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.22em;
  line-height: 1.4;
  color: var(--lime);
}

.section--paper .eyebrow { color: var(--turf); }

.section-title {
  font-size: clamp(28px, 4vw, 56px);
  font-weight: 900;
  letter-spacing: -0.02em;
  line-height: 1.06;
}

.section-lead {
  max-width: 56ch;
  font-size: clamp(15px, 1.2vw, 17px);
  line-height: 1.62;
  opacity: 0.86;
}

.chapter {
  display: grid;
  grid-template-columns: minmax(0, auto) minmax(0, 1fr);
  gap: clamp(12px, 2vw, 30px);
  align-items: start;
}

.chapter__num {
  font-family: var(--font-mono);
  font-size: clamp(26px, 4vw, 46px);
  font-weight: 700;
  line-height: 0.9;
  letter-spacing: -0.02em;
  color: var(--lime);
}

.section--paper .chapter__num { color: var(--turf); }

.chapter__body { min-width: 0; }

.grid {
  display: grid;
  gap: clamp(14px, 2vw, 24px);
}

.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)); }

@media (max-width: 899px) {
  .grid--3,
  .grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 599px) {
  .grid--2,
  .grid--3,
  .grid--4 { grid-template-columns: minmax(0, 1fr); }
  .chapter { grid-template-columns: minmax(0, 1fr); }
}

.stack {
  display: flex;
  flex-direction: column;
  gap: var(--gap, 16px);
}

.cluster {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px 14px;
}

.rule {
  height: 1px;
  border: 0;
  margin: 0;
  background: currentColor;
  opacity: 0.18;
}

.mono {
  font-family: var(--font-mono);
  letter-spacing: 0.1em;
}

.num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.04em;
}

/* 图片容器基础规则 */
.figure {
  position: relative;
  display: block;
  overflow: hidden;
  background: var(--ink-deep);
  border: 1px solid var(--line);
  border-radius: 2px;
}

.section--paper .figure { border-color: var(--line-ink); }

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

.figure--16x9 { aspect-ratio: 16 / 9; }
.figure--4x5 { aspect-ratio: 4 / 5; }
.figure--1x1 { aspect-ratio: 1 / 1; }
.figure--21x9 { aspect-ratio: 21 / 9; }

.figure__cap {
  position: absolute;
  left: 0;
  bottom: 0;
  right: 0;
  padding: 8px 12px;
  background: linear-gradient(
    to top,
    rgba(7, 28, 23, 0.92),
    rgba(7, 28, 23, 0)
  );
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.12em;
  color: var(--paper);
}

/* 卡片与标签 */
.card {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: clamp(16px, 2.2vw, 24px);
  background: rgba(242, 235, 221, 0.04);
  border: 1px solid var(--line);
  border-radius: 2px;
}

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

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 9px;
  border: 1px solid currentColor;
  border-radius: 2px;
  font-family: var(--font-mono);
  font-size: 10.5px;
  font-weight: 700;
  letter-spacing: 0.1em;
  line-height: 1.5;
}

.tag--lime { color: var(--lime); }

.tag--rust {
  background: var(--rust);
  border-color: var(--rust);
  color: var(--white);
}

/* 数据条 */
.meter { display: grid; gap: 6px; }

.meter__track {
  position: relative;
  height: 6px;
  background: rgba(242, 235, 221, 0.16);
  overflow: hidden;
}

.section--paper .meter__track { background: rgba(20, 23, 22, 0.14); }

.meter__fill {
  display: block;
  height: 100%;
  width: var(--v, 50%);
  background: var(--turf);
}

.meter__fill--lime { background: var(--lime); }
.meter__fill--rust { background: var(--rust); }

/* 面包屑 */
.crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  padding-block: 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  line-height: 1.6;
  opacity: 0.74;
}

.crumbs a {
  text-decoration: none;
  transition: opacity 0.16s var(--ease);
}

.crumbs a:hover { opacity: 1; text-decoration: underline; }

.crumbs__sep { opacity: 0.5; }

.crumbs [aria-current="page"] { font-weight: 700; }

/* ---------- 13. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  min-height: 44px;
  padding: 11px 20px;
  border: 1px solid var(--line-2);
  border-radius: 2px;
  background: transparent;
  color: var(--paper);
  font-family: var(--font-sans);
  font-size: 14px;
  font-weight: 800;
  letter-spacing: 0.03em;
  line-height: 1.2;
  text-decoration: none;
  cursor: pointer;
  transition: background 0.16s var(--ease), color 0.16s var(--ease),
    border-color 0.16s var(--ease);
}

.btn:hover {
  background: rgba(242, 235, 221, 0.1);
  border-color: var(--paper);
}

.btn--lime {
  background: var(--lime);
  border-color: var(--lime);
  color: var(--steel);
}

.btn--lime:hover {
  background: var(--paper);
  border-color: var(--paper);
  color: var(--steel);
}

.btn--ink {
  background: var(--ink);
  border-color: var(--ink);
  color: var(--paper);
}

.btn--ink:hover {
  background: var(--steel);
  border-color: var(--steel);
}

/* ---------- 14. 滚动显现 ---------- */
[data-reveal] {
  transition: opacity 0.5s var(--ease), transform 0.5s var(--ease);
}

[data-reveal].is-reveal {
  opacity: 0;
  transform: translateY(16px);
}

[data-reveal].is-in {
  opacity: 1;
  transform: translateY(0);
}

/* ---------- 15. 减弱动效 ---------- */
@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;
  }

  [data-reveal],
  [data-reveal].is-reveal {
    opacity: 1;
    transform: none;
  }
}