/* ============================================================
   爱体育 · 共享外壳样式 / assets/site.css
   训练馆混凝土体系：深灰基底 + 活力橙行动 + 荧光青数据
   ============================================================ */

/* ---------- 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, fieldset { margin: 0; }

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

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

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

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

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

/* ---------- 2. TOKENS ---------- */
:root {
  --c-concrete: #1E2023;
  --c-graphite: #2A2D31;
  --c-steel: #43484E;
  --c-dust: #8A9098;
  --c-bone: #F2F3F0;
  --c-orange: #FF5A1F;
  --c-orange-deep: #C43D0B;
  --c-cyan: #00E5FF;
  --c-cyan-deep: #00707F;
  --c-alert: #E5484D;

  --font-display: "Impact", "Haettenschweiler", "Arial Narrow Bold", "PingFang SC", "Noto Sans SC", "Microsoft YaHei", sans-serif;
  --font-body: "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;

  --util-h: 34px;
  --bar-h: 56px;
  --rail-w: 0px;

  --ease: cubic-bezier(0.2, 0.8, 0.2, 1);
  --gap: clamp(1rem, 2.2vw, 1.6rem);
  --content-max: 1320px;
  --cut: 14px;
}

/* ---------- 3. 中文排版与基础 ---------- */
body {
  margin: 0;
  padding-top: calc(var(--util-h) + var(--bar-h));
  padding-bottom: 5.25rem;
  padding-left: var(--rail-w);
  background-color: var(--c-concrete);
  background-image: repeating-linear-gradient(115deg, rgba(255, 255, 255, 0.014) 0 1px, transparent 1px 5px);
  color: var(--c-bone);
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.7;
  letter-spacing: 0.01em;
  word-break: break-word;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 900;
  line-height: 1.04;
  letter-spacing: -0.01em;
  text-wrap: balance;
}

h1 { font-size: clamp(2.5rem, 6vw, 4.8rem); }
h2 { font-size: clamp(1.85rem, 3.4vw, 2.9rem); }
h3 { font-size: clamp(1.2rem, 1.8vw, 1.55rem); line-height: 1.16; }
h4 { font-size: 1.05rem; line-height: 1.25; }

p { max-width: 68ch; }

::selection {
  background: var(--c-orange);
  color: #141618;
}

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

[id] { scroll-margin-top: calc(var(--util-h) + 24px); }

/* ---------- 4. 通用排版组件 ---------- */
.display {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(2.9rem, 9vw, 7rem);
  line-height: 0.88;
  letter-spacing: -0.03em;
}

.display--skew { transform: skewX(-6deg); transform-origin: left bottom; }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.76rem;
  font-weight: 800;
  letter-spacing: 0.22em;
  color: var(--c-orange);
}

.eyebrow::before {
  content: "";
  width: 26px;
  height: 3px;
  background: var(--c-orange);
  transform: skewX(-20deg);
}

.lede {
  font-size: clamp(1.02rem, 1.5vw, 1.22rem);
  line-height: 1.75;
  color: var(--c-bone);
  opacity: 0.9;
}

.muted { color: var(--c-dust); }

.data {
  font-variant-numeric: tabular-nums;
  font-feature-settings: "tnum" 1;
  letter-spacing: 0.02em;
}

/* ---------- 5. 布局 ---------- */
.container {
  width: 100%;
  max-width: var(--content-max);
  margin-inline: auto;
  padding-inline: clamp(1rem, 3vw, 2.5rem);
}

.section { padding-block: clamp(2.5rem, 6vw, 5rem); }

.section--bone {
  background: var(--c-bone);
  color: var(--c-concrete);
}

.section--bone .muted { color: #5B6066; }
.section--bone .eyebrow { color: var(--c-orange-deep); }
.section--bone .eyebrow::before { background: var(--c-orange-deep); }
.section--bone .btn--ghost { color: var(--c-concrete); border-color: #B9BDBA; }
.section--bone .btn--ghost:hover { color: var(--c-orange-deep); border-color: var(--c-orange-deep); }

.grid { display: grid; gap: var(--gap); }
.grid--2 { grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); }
.grid--3 { grid-template-columns: repeat(auto-fit, minmax(210px, 1fr)); }

.layout-split,
.layout-aside {
  display: grid;
  gap: var(--gap);
  grid-template-columns: 1fr;
}

@media (min-width: 1024px) {
  .layout-split { grid-template-columns: 7fr 5fr; align-items: start; }
  .layout-aside { grid-template-columns: 7fr 3fr; align-items: start; }
}

/* ---------- 6. 按钮 / 标签 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.85rem 1.45rem;
  font-family: var(--font-body);
  font-size: 0.94rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  line-height: 1.1;
  border: 2px solid transparent;
  clip-path: polygon(0 0, calc(100% - 12px) 0, 100% 12px, 100% 100%, 12px 100%, 0 calc(100% - 12px));
  transition: transform 0.18s var(--ease), background-color 0.18s var(--ease),
    color 0.18s var(--ease), border-color 0.18s var(--ease);
}

.btn:active { transform: translateY(1px); }

.btn--primary {
  background: var(--c-orange);
  color: #141618;
}

.btn--primary:hover {
  background: var(--c-orange-deep);
  color: var(--c-bone);
  transform: translateY(-2px);
}

.btn--ghost {
  background: transparent;
  border-color: var(--c-steel);
  color: var(--c-bone);
}

.btn--ghost:hover {
  border-color: var(--c-cyan);
  color: var(--c-cyan);
  transform: translateY(-2px);
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.2rem 0.6rem;
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.12em;
  color: var(--c-cyan);
  background: rgba(0, 229, 255, 0.08);
  border: 1px solid rgba(0, 229, 255, 0.45);
}

.tag--orange {
  color: var(--c-orange);
  background: rgba(255, 90, 31, 0.12);
  border-color: rgba(255, 90, 31, 0.5);
}

/* ---------- 7. 面板 / 卡片 ---------- */
.panel,
.card {
  position: relative;
  background: var(--c-graphite);
  border: 1px solid var(--c-steel);
  padding: clamp(1.1rem, 2.4vw, 1.75rem);
  clip-path: polygon(0 0, calc(100% - var(--cut)) 0, 100% var(--cut), 100% 100%,
      var(--cut) 100%, 0 calc(100% - var(--cut)));
}

.panel--bone {
  background: var(--c-bone);
  color: var(--c-concrete);
  border-color: transparent;
}

.panel--accent { border-left: 4px solid var(--c-orange); }

.card {
  padding: 1.15rem;
  transition: transform 0.2s var(--ease), border-color 0.2s var(--ease);
}

.card:hover {
  transform: translateY(-4px);
  border-color: var(--c-orange);
}

/* ---------- 8. 图片容器基础 ---------- */
.img-frame {
  position: relative;
  display: block;
  overflow: hidden;
  isolation: isolate;
  aspect-ratio: 16 / 10;
  background: linear-gradient(135deg, #33383D 0%, #2A2D31 42%, #1E2023 100%);
}

.img-frame img,
.img-frame picture,
.img-frame video {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: contrast(1.1) saturate(1.05);
}

.img-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, rgba(30, 32, 35, 0) 38%, rgba(30, 32, 35, 0.78) 100%);
}

.img-frame--tint::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 1;
  background: linear-gradient(135deg, rgba(255, 90, 31, 0.34), rgba(0, 229, 255, 0.18));
  mix-blend-mode: screen;
}

.img-frame--wide { aspect-ratio: 21 / 9; }
.img-frame--tall { aspect-ratio: 3 / 4; }
.img-frame--square { aspect-ratio: 1 / 1; }

.img-frame--cut {
  clip-path: polygon(0 0, calc(100% - 18px) 0, 100% 18px, 100% 100%, 18px 100%, 0 calc(100% - 18px));
}

.img-frame-caption {
  display: block;
  margin-top: 0.55rem;
  font-size: 0.8rem;
  line-height: 1.6;
  color: var(--c-dust);
}

/* ---------- 9. 面包屑 ---------- */
.breadcrumb { padding-block: 0.6rem; }

.breadcrumb-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  font-size: 0.82rem;
  color: var(--c-dust);
}

.breadcrumb-list li {
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.breadcrumb-list li + li::before {
  content: "/";
  color: var(--c-steel);
}

.breadcrumb-link { color: var(--c-dust); }
.breadcrumb-link:hover { color: var(--c-orange); }
.breadcrumb-current { color: var(--c-bone); font-weight: 600; }

.section--bone .breadcrumb-current { color: var(--c-concrete); }

/* ---------- 10. 章节索引 ---------- */
.toc-link {
  display: block;
  padding: 0.35rem 0 0.35rem 0.85rem;
  border-left: 1px solid var(--c-steel);
  color: var(--c-dust);
  font-size: 0.9rem;
  line-height: 1.5;
  transition: color 0.18s var(--ease), border-color 0.18s var(--ease);
}

.toc-link:hover { color: var(--c-bone); }

.toc-link.is-current {
  color: var(--c-cyan);
  border-left-color: var(--c-cyan);
  font-weight: 600;
}

/* ---------- 11. SKIP LINK ---------- */
.skip-link {
  position: fixed;
  top: 0.5rem;
  left: 0.5rem;
  z-index: 200;
  padding: 0.7rem 1.15rem;
  background: var(--c-orange);
  color: #141618;
  font-weight: 800;
  letter-spacing: 0.04em;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 8px), calc(100% - 8px) 100%, 0 100%);
  transform: translateY(-180%);
  transition: transform 0.18s var(--ease);
}

.skip-link:focus,
.skip-link:focus-visible {
  transform: translateY(0);
  outline: 2px solid var(--c-cyan);
  outline-offset: 2px;
}

/* ---------- 12. HEADER ---------- */
.site-header {
  position: relative;
  z-index: 80;
}

/* 12.1 品牌说明细条 */
.utility-bar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--util-h);
  z-index: 96;
  background: var(--c-graphite);
  border-top: 3px solid var(--c-orange);
  border-bottom: 1px solid var(--c-steel);
}

.utility-inner {
  height: 100%;
  display: flex;
  align-items: center;
  gap: 0.85rem;
  padding-inline: clamp(0.75rem, 2.5vw, 1.5rem);
  overflow: hidden;
}

.utility-brandline {
  font-size: 0.76rem;
  font-weight: 800;
  letter-spacing: 0.14em;
  color: var(--c-bone);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.utility-status {
  margin-left: auto;
  font-size: 0.73rem;
  color: var(--c-dust);
  white-space: nowrap;
  display: none;
}

.version-badge {
  flex: none;
  margin-left: auto;
  padding: 0.12rem 0.55rem;
  font-size: 0.7rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  color: #141618;
  background: var(--c-orange);
  font-variant-numeric: tabular-nums;
  clip-path: polygon(6px 0, 100% 0, 100% calc(100% - 6px), calc(100% - 6px) 100%, 0 100%, 0 6px);
  transition: background-color 0.18s var(--ease);
}

.version-badge:hover { background: var(--c-cyan); }

/* 12.2 移动端贴顶品牌条 */
.nav-rail {
  position: fixed;
  top: var(--util-h);
  left: 0;
  right: 0;
  height: var(--bar-h);
  z-index: 91;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding-inline: clamp(0.75rem, 3vw, 1.25rem);
  background-color: var(--c-concrete);
  background-image: linear-gradient(118deg, rgba(255, 90, 31, 0.2) 0%, rgba(255, 90, 31, 0) 52%);
  border-bottom: 1px solid var(--c-steel);
}

.rail-mark {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-display);
  font-size: 1.15rem;
  font-weight: 900;
  letter-spacing: 0.01em;
  color: var(--c-bone);
}

.rail-mark-bar {
  display: block;
  width: 5px;
  height: 22px;
  background: var(--c-orange);
  transform: skewX(-14deg);
}

.rail-mark-text { white-space: nowrap; }

/* 12.3 主导航（移动端为底部抽屉） */
.rail-nav {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 94;
  display: grid;
  gap: 0.9rem;
  max-height: 82vh;
  overflow-y: auto;
  padding: 1.15rem clamp(1rem, 4vw, 1.6rem) calc(1.3rem + env(safe-area-inset-bottom));
  background: var(--c-graphite);
  border-top: 2px solid var(--c-orange);
  clip-path: polygon(0 18px, 18px 0, 100% 0, 100% 100%, 0 100%);
  transform: translateY(112%);
  visibility: hidden;
  transition: transform 0.28s var(--ease), visibility 0.28s var(--ease);
}

.rail-nav[data-open] {
  transform: translateY(0);
  visibility: visible;
}

.rail-nav-list {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.45rem;
}

.rail-link {
  position: relative;
  display: flex;
  align-items: center;
  padding: 0.78rem 0.85rem;
  font-size: 0.98rem;
  font-weight: 600;
  color: var(--c-bone);
  background: var(--c-concrete);
  border-left: 3px solid transparent;
  transition: background-color 0.18s var(--ease), color 0.18s var(--ease),
    border-color 0.18s var(--ease);
}

.rail-link:hover,
.rail-link:focus-visible {
  color: var(--c-cyan);
  border-left-color: var(--c-cyan);
}

.rail-link[aria-current="page"] {
  color: var(--c-bone);
  background: rgba(255, 90, 31, 0.16);
  border-left-color: var(--c-orange);
}

.rail-cta {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0.9rem 1rem;
  font-size: 0.94rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  color: #141618;
  background: var(--c-orange);
  clip-path: polygon(0 0, calc(100% - 14px) 0, 100% 14px, 100% 100%, 14px 100%, 0 calc(100% - 14px));
  transition: background-color 0.18s var(--ease), color 0.18s var(--ease), transform 0.18s var(--ease);
}

.rail-cta:hover {
  background: var(--c-orange-deep);
  color: var(--c-bone);
  transform: translateY(-2px);
}

/* 12.4 移动抽屉按钮 */
.nav-toggle {
  position: fixed;
  right: clamp(0.75rem, 3vw, 1.25rem);
  bottom: calc(0.9rem + env(safe-area-inset-bottom));
  z-index: 98;
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  padding: 0.72rem 1.1rem;
  font-size: 0.82rem;
  font-weight: 800;
  letter-spacing: 0.14em;
  color: #141618;
  background: var(--c-orange);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.48);
  clip-path: polygon(10px 0, 100% 0, 100% calc(100% - 10px), calc(100% - 10px) 100%, 0 100%, 0 10px);
  transition: background-color 0.18s var(--ease);
}

.nav-toggle:hover { background: var(--c-cyan); }

.nav-toggle-label { line-height: 1; }

.nav-toggle-bars {
  display: grid;
  gap: 3px;
  width: 14px;
}

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

.nav-toggle[aria-expanded="true"] .nav-toggle-bars span:nth-child(1) {
  transform: translateY(5px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bars span:nth-child(2) { opacity: 0; }

.nav-toggle[aria-expanded="true"] .nav-toggle-bars span:nth-child(3) {
  transform: translateY(-5px) rotate(-45deg);
}

/* 12.5 抽屉遮罩 */
.nav-scrim {
  position: fixed;
  inset: 0;
  z-index: 93;
  background: rgba(12, 13, 15, 0.7);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.24s var(--ease);
}

.site-header[data-nav-open] .nav-scrim {
  opacity: 1;
  pointer-events: auto;
}

/* 12.6 桌面：左侧竖向栏目轨 */
@media (min-width: 640px) {
  .utility-status { display: block; }
  .version-badge { margin-left: 0; }
}

@media (min-width: 1024px) {
  :root { --rail-w: 176px; }

  body {
    padding-top: var(--util-h);
    padding-left: var(--rail-w);
    padding-bottom: 0;
  }

  .utility-status { margin-left: auto; }

  .nav-rail {
    top: var(--util-h);
    bottom: 0;
    right: auto;
    width: var(--rail-w);
    height: auto;
    flex-direction: column;
    align-items: flex-start;
    gap: 1.6rem;
    padding: 1.7rem 1.1rem 1.5rem;
    border-right: 1px solid var(--c-steel);
    border-bottom: 0;
    background-image: linear-gradient(168deg, rgba(255, 90, 31, 0.2) 0%, rgba(255, 90, 31, 0) 44%),
      repeating-linear-gradient(0deg, rgba(255, 255, 255, 0.022) 0 1px, transparent 1px 4px);
  }

  .rail-mark { font-size: 1.35rem; }
  .rail-mark-bar { height: 26px; }

  .rail-nav {
    position: static;
    display: flex;
    flex-direction: column;
    gap: 0.3rem;
    flex: 1 1 auto;
    width: 100%;
    max-height: none;
    overflow: visible;
    padding: 0;
    background: transparent;
    border: 0;
    clip-path: none;
    transform: none;
    visibility: visible;
    transition: none;
  }

  .rail-nav-list {
    position: relative;
    grid-template-columns: 1fr;
    gap: 0.15rem;
    width: 100%;
  }

  .rail-nav-list::before {
    content: "";
    position: absolute;
    left: 0;
    top: 0.5rem;
    bottom: 0.5rem;
    width: 1px;
    background: var(--c-steel);
  }

  .rail-link {
    background: transparent;
    border-left: 0;
    padding: 0.6rem 0.5rem 0.6rem 1rem;
    font-size: 0.94rem;
    color: var(--c-dust);
  }

  .rail-link:hover,
  .rail-link:focus-visible {
    color: var(--c-bone);
    background: rgba(255, 255, 255, 0.05);
  }

  .rail-link[aria-current="page"] {
    color: var(--c-bone);
    background: rgba(255, 90, 31, 0.14);
  }

  .rail-link[aria-current="page"]::after {
    content: "";
    position: absolute;
    left: -1px;
    top: 50%;
    width: 3px;
    height: 18px;
    background: var(--c-orange);
    transform: translateY(-50%);
  }

  .rail-cta {
    margin-top: auto;
    width: 100%;
    font-size: 0.88rem;
    text-align: center;
  }

  .nav-toggle,
  .nav-scrim { display: none; }
}

/* ---------- 13. FOOTER ---------- */
.site-footer {
  position: relative;
  margin-top: clamp(2.5rem, 6vw, 5rem);
  background-color: var(--c-graphite);
  background-image: repeating-linear-gradient(90deg, rgba(255, 255, 255, 0.016) 0 1px, transparent 1px 6px);
  border-top: 1px solid var(--c-steel);
}

.footer-rule {
  height: 6px;
  background:
    linear-gradient(90deg,
      var(--c-orange) 0 20%,
      transparent 20% 26%,
      var(--c-cyan) 26% 30%,
      transparent 30% 100%);
}

.footer-inner {
  display: grid;
  gap: clamp(1.75rem, 4vw, 2.5rem);
  padding-block: clamp(2.25rem, 5vw, 3.5rem) clamp(1.75rem, 4vw, 2.75rem);
}

@media (min-width: 768px) {
  .footer-inner { grid-template-columns: 1fr 1fr; }
  .footer-brand { grid-column: 1 / -1; }
}

@media (min-width: 1024px) {
  .footer-inner {
    grid-template-columns: 1.55fr 0.85fr 1.25fr 1fr;
    align-items: start;
  }

  .footer-brand { grid-column: auto; }
  .footer-nav { transform: translateY(16px); }
  .footer-contact { transform: translateY(-12px); }
}

.footer-brand::before {
  content: "";
  display: block;
  width: 58px;
  height: 5px;
  margin-bottom: 1rem;
  background: var(--c-orange);
  transform: skewX(-18deg);
}

.footer-brandline {
  max-width: 22ch;
  font-family: var(--font-display);
  font-size: clamp(1.5rem, 2.6vw, 2.15rem);
  font-weight: 900;
  line-height: 1.06;
  letter-spacing: -0.01em;
  color: var(--c-bone);
}

.footer-update {
  margin-top: 0.85rem;
  max-width: 34ch;
  font-size: 0.88rem;
  line-height: 1.7;
  color: var(--c-dust);
}

.footer-cta { margin-top: 1.35rem; }

.footer-col-title {
  margin-bottom: 0.9rem;
  font-size: 0.74rem;
  font-weight: 800;
  letter-spacing: 0.2em;
  color: var(--c-cyan);
}

.footer-nav-list {
  display: grid;
  gap: 0.4rem;
}

.footer-link {
  display: inline-block;
  padding-block: 0.15rem;
  font-size: 0.94rem;
  color: var(--c-bone);
  border-bottom: 1px solid transparent;
  transition: color 0.18s var(--ease), border-color 0.18s var(--ease);
}

.footer-link:hover,
.footer-link:focus-visible {
  color: var(--c-orange);
  border-bottom-color: var(--c-orange);
}

.footer-contact-list {
  display: grid;
  gap: 0.65rem;
}

.footer-contact-item {
  display: grid;
  gap: 0.05rem;
}

.footer-contact-key {
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  color: var(--c-dust);
}

.footer-contact-value {
  font-size: 0.9rem;
  color: var(--c-bone);
  word-break: break-all;
}

.footer-service {
  margin-top: 0.95rem;
  max-width: 34ch;
  font-size: 0.8rem;
  line-height: 1.65;
  color: var(--c-dust);
}

.footer-legal {
  padding-top: 1rem;
  border-top: 1px solid var(--c-steel);
}

.footer-legal-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.3rem 1.1rem;
  margin-bottom: 1rem;
}

.footer-record {
  font-variant-numeric: tabular-nums;
  font-size: 0.8rem;
  letter-spacing: 0.06em;
  color: var(--c-dust);
}

.footer-meta {
  margin-top: 0.35rem;
  font-size: 0.78rem;
  color: var(--c-steel);
}

/* ---------- 14. 滚动进度 / 返回顶部 ---------- */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  z-index: 120;
  pointer-events: none;
}

.scroll-progress-bar {
  height: 100%;
  width: 100%;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background: linear-gradient(90deg, var(--c-orange) 0%, var(--c-cyan) 100%);
  transition: transform 0.1s linear;
}

.to-top {
  position: fixed;
  right: clamp(0.9rem, 3vw, 1.5rem);
  bottom: calc(4.7rem + env(safe-area-inset-bottom));
  z-index: 92;
  display: grid;
  place-items: center;
  width: 46px;
  height: 46px;
  font-size: 1.05rem;
  font-weight: 800;
  color: var(--c-cyan);
  background: var(--c-graphite);
  border: 1px solid var(--c-steel);
  clip-path: polygon(8px 0, 100% 0, 100% calc(100% - 8px), calc(100% - 8px) 100%, 0 100%, 0 8px);
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: opacity 0.22s var(--ease), transform 0.22s var(--ease), visibility 0.22s var(--ease),
    background-color 0.18s var(--ease), color 0.18s var(--ease);
}

.to-top.is-active {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.to-top:hover {
  background: var(--c-orange);
  color: #141618;
}

@media (min-width: 1024px) {
  .to-top { bottom: 1.5rem; }
}

/* ---------- 15. 显现动画 ---------- */
[data-reveal] {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.42s var(--ease), transform 0.42s var(--ease);
}

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

/* ---------- 16. 减少动态 ---------- */
@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] {
    opacity: 1 !important;
    transform: none !important;
  }

  .rail-nav,
  .rail-link,
  .btn,
  .to-top { transition: none; }
}