/* ==========================================================================
   B体育入口 · /assets/site.css
   共享层：reset / 变量 / 中文排版 / 头部轨道 / 页脚 / 通用组件
   ========================================================================== */

/* ---------- 1. 设计变量 ---------- */
:root {
  --c-ink: #070B10;
  --c-ink-2: #0E1620;
  --c-cyan: #26F0E0;
  --c-cyan-mist: #7FF7EC;
  --c-orange: #FF5B1F;
  --c-orange-glow: #FF8A4D;
  --c-white: #F2F7F8;
  --c-steel: #8FA3AD;
  --c-line: #1B3A42;
  --c-glass: rgba(242, 247, 248, 0.08);
  --c-glass-2: rgba(242, 247, 248, 0.035);

  --fs-12: 0.75rem;
  --fs-14: 0.875rem;
  --fs-16: 1rem;
  --fs-18: 1.125rem;
  --fs-24: 1.5rem;
  --fs-32: 2rem;
  --fs-48: 3rem;
  --fs-72: 4.5rem;
  --fs-120: 7.5rem;

  --font-sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei",
    "Helvetica Neue", Helvetica, Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas,
    "Liberation Mono", monospace;

  --rail-w: 100px;
  --shell: 1280px;
  --gutter: 20px;
  --ease: cubic-bezier(0.22, 0.68, 0.3, 1);
}

/* ---------- 2. Reset ---------- */
*,
*::before,
*::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  scroll-behavior: smooth;
  background-color: var(--c-ink);
  background-image:
    radial-gradient(58vw 46vh at 84% 2%, rgba(38, 240, 224, 0.09), transparent 62%),
    radial-gradient(46vw 42vh at 4% 92%, rgba(255, 91, 31, 0.075), transparent 66%);
  background-attachment: fixed;
  background-repeat: no-repeat;
}

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

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

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

/* ---------- 3. 基础排版 ---------- */
body {
  min-height: 100vh;
  padding-top: 64px;
  background: var(--c-ink);
  color: var(--c-white);
  font-family: var(--font-sans);
  font-size: var(--fs-16);
  line-height: 1.75;
  letter-spacing: 0.01em;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

h1, .h1,
h2, .h2,
h3, .h3 {
  font-weight: 800;
  letter-spacing: -0.015em;
  line-height: 1.18;
  text-wrap: balance;
}

h1, .h1 { font-size: clamp(1.9rem, 5.2vw, 3.25rem); line-height: 1.1; }
h2, .h2 { font-size: clamp(1.4rem, 3.2vw, 2rem); }
h3, .h3 { font-size: var(--fs-18); font-weight: 700; line-height: 1.45; }

p { text-wrap: pretty; }

strong { font-weight: 700; color: var(--c-white); }

code, .mono {
  font-family: var(--font-mono);
  font-size: 0.92em;
  letter-spacing: 0.02em;
}

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

/* ---------- 4. 骨架容器 ---------- */
.container {
  width: 100%;
  max-width: var(--shell);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section {
  position: relative;
  padding-block: clamp(44px, 6.5vw, 92px);
}

.section--band {
  background: linear-gradient(180deg, #0B131B 0%, #080E14 100%);
  border-block: 1px solid var(--c-line);
}

.divider {
  height: 1px;
  border: 0;
  margin: 0;
  background: linear-gradient(90deg, transparent, #22434D 18%, #22434D 82%, transparent);
}

/* ---------- 5. Skip link ---------- */
.skip-link {
  position: fixed;
  top: -120px;
  left: 14px;
  z-index: 200;
  padding: 11px 18px;
  font-size: var(--fs-14);
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--c-ink);
  background: var(--c-cyan);
  border-radius: 2px;
  box-shadow: 0 10px 30px -10px rgba(38, 240, 224, 0.9);
  transition: top 0.22s var(--ease);
}

.skip-link:focus {
  top: 14px;
  outline-offset: 2px;
}

/* ---------- 6. 头部轨道 ---------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding-inline: 16px;
  background: rgba(7, 11, 16, 0.84);
  -webkit-backdrop-filter: blur(16px) saturate(150%);
  backdrop-filter: blur(16px) saturate(150%);
  border-bottom: 1px solid var(--c-line);
  box-shadow: 0 18px 40px -30px rgba(0, 0, 0, 0.95);
}

/* 品牌 */
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-width: 0;
  color: var(--c-white);
}

.brand__mark {
  flex: none;
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  font-family: var(--font-mono);
  font-size: 17px;
  font-weight: 700;
  line-height: 1;
  color: var(--c-ink);
  background: linear-gradient(145deg, var(--c-cyan) 0%, #12B7AE 100%);
  clip-path: polygon(0 0, 100% 0, 100% 72%, 72% 100%, 0 100%);
  box-shadow: 0 0 20px rgba(38, 240, 224, 0.42);
}

.brand__text {
  display: flex;
  flex-direction: column;
  line-height: 1.05;
  min-width: 0;
}

.brand__name {
  font-size: 15px;
  font-weight: 800;
  letter-spacing: 0.06em;
}

.brand__sub {
  font-family: var(--font-mono);
  font-size: 9.5px;
  letter-spacing: 0.34em;
  color: var(--c-cyan);
  text-transform: uppercase;
}

/* 移动导航按钮 */
.nav-toggle {
  flex: none;
  display: inline-flex;
  flex-direction: column;
  align-items: stretch;
  justify-content: center;
  gap: 5px;
  width: 44px;
  height: 44px;
  padding: 0 11px;
  border: 1px solid var(--c-line);
  border-radius: 2px;
  background: var(--c-glass);
  clip-path: polygon(0 0, 100% 0, 100% 74%, 74% 100%, 0 100%);
  transition: border-color 0.2s var(--ease), background 0.2s var(--ease);
}

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

.nav-toggle__bar {
  display: block;
  height: 2px;
  width: 100%;
  background: var(--c-white);
  border-radius: 1px;
  transition: transform 0.28s var(--ease), opacity 0.18s linear, background 0.2s linear;
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
  background: var(--c-orange);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(2) {
  opacity: 0;
  transform: scaleX(0.2);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
  background: var(--c-orange);
}

/* 导航面板（移动端为抽屉） */
.nav {
  position: fixed;
  top: 64px;
  left: 0;
  right: 0;
  max-height: calc(100vh - 64px);
  overflow-y: auto;
  padding: 8px 16px 26px;
  background: linear-gradient(180deg, #0B131B 0%, #070B10 100%);
  border-bottom: 1px solid var(--c-line);
  box-shadow: 0 30px 70px -20px rgba(0, 0, 0, 0.85);
  visibility: hidden;
  opacity: 0;
  transform: translateY(-10px);
  transition: opacity 0.26s var(--ease), transform 0.26s var(--ease), visibility 0.26s linear;
}

.nav[data-open="true"] {
  visibility: visible;
  opacity: 1;
  transform: none;
}

.nav__list {
  display: flex;
  flex-direction: column;
}

.nav__item + .nav__item {
  border-top: 1px solid rgba(27, 58, 66, 0.72);
}

.nav__link {
  display: flex;
  align-items: center;
  gap: 11px;
  padding: 13px 2px;
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0.07em;
  color: var(--c-white);
  transition: color 0.2s var(--ease), background 0.2s var(--ease);
}

.nav__dot {
  flex: none;
  width: 6px;
  height: 6px;
  background: #24454F;
  transform: rotate(45deg);
  transition: background 0.2s var(--ease), box-shadow 0.2s var(--ease);
}

.nav__label { display: block; }

.nav__link:hover { color: var(--c-cyan); }
.nav__link:hover .nav__dot {
  background: var(--c-cyan);
  box-shadow: 0 0 10px rgba(38, 240, 224, 0.75);
}

.nav__link[aria-current="page"] { color: var(--c-cyan); }
.nav__link[aria-current="page"] .nav__dot {
  background: var(--c-orange);
  box-shadow: 0 0 12px rgba(255, 91, 31, 0.85);
}

.nav__cta {
  display: block;
  margin-top: 18px;
  padding: 13px 10px;
  font-size: 13px;
  font-weight: 800;
  line-height: 1.3;
  letter-spacing: 0.06em;
  text-align: center;
  color: var(--c-ink);
  background: linear-gradient(135deg, var(--c-orange) 0%, var(--c-orange-glow) 100%);
  clip-path: polygon(0 0, 100% 0, 100% 78%, 84% 100%, 0 100%);
  box-shadow: 0 14px 34px -16px rgba(255, 91, 31, 0.95);
  transition: filter 0.2s var(--ease), transform 0.2s var(--ease);
}

.nav__cta:hover {
  filter: brightness(1.08);
  transform: translateY(-1px);
}

body.nav-open { overflow: hidden; }

/* ---------- 7. 页脚 ---------- */
.site-footer {
  position: relative;
  margin-top: clamp(56px, 8vw, 104px);
  padding: clamp(44px, 6vw, 72px) 0 26px;
  background: linear-gradient(180deg, #070B10 0%, #0B131B 42%, #070B10 100%);
  border-top: 1px solid var(--c-line);
  overflow: hidden;
}

.site-footer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--c-cyan), var(--c-orange), transparent);
  opacity: 0.6;
}

.site-footer::after {
  content: "";
  position: absolute;
  top: -50%;
  right: -12%;
  width: 60%;
  height: 180%;
  background: radial-gradient(closest-side, rgba(38, 240, 224, 0.1), transparent 72%);
  pointer-events: none;
}

.site-footer .container { position: relative; z-index: 1; }

.footer__top {
  display: grid;
  grid-template-columns: 1fr;
  gap: 34px;
}

.footer__brand { min-width: 0; }

.footer__logo {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
}

.footer__logo-mark {
  flex: none;
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  font-family: var(--font-mono);
  font-size: 20px;
  font-weight: 700;
  line-height: 1;
  color: var(--c-ink);
  background: linear-gradient(145deg, var(--c-cyan) 0%, #0F9C95 100%);
  clip-path: polygon(0 0, 100% 0, 100% 72%, 72% 100%, 0 100%);
}

.footer__logo-text {
  font-size: 20px;
  font-weight: 800;
  letter-spacing: 0.03em;
}

.footer__tagline {
  max-width: 30ch;
  font-size: 15px;
  line-height: 1.8;
  color: rgba(242, 247, 248, 0.72);
}

.footer__badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-top: 16px;
  padding: 5px 11px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--c-cyan);
  background: rgba(38, 240, 224, 0.09);
  border: 1px solid rgba(38, 240, 224, 0.3);
  border-radius: 2px;
}

.footer__badge::before {
  content: "";
  width: 5px;
  height: 5px;
  background: var(--c-orange);
  transform: rotate(45deg);
}

.footer__col { min-width: 0; }

.footer__title {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 16px;
  padding-bottom: 11px;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  line-height: 1.4;
  letter-spacing: 0.22em;
  color: var(--c-steel);
  text-transform: uppercase;
  border-bottom: 1px solid var(--c-line);
}

.footer__title::before {
  content: "";
  width: 16px;
  height: 1px;
  background: var(--c-cyan);
}

.footer__list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer__link {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  font-size: 15px;
  color: rgba(242, 247, 248, 0.78);
  transition: color 0.2s var(--ease), transform 0.2s var(--ease);
}

.footer__link::before {
  content: "";
  flex: none;
  width: 5px;
  height: 5px;
  background: #24454F;
  transform: rotate(45deg);
  transition: background 0.2s var(--ease);
}

.footer__link:hover {
  color: var(--c-cyan);
  transform: translateX(2px);
}

.footer__link:hover::before { background: var(--c-orange); }

.footer__contact {
  display: flex;
  flex-direction: column;
  gap: 9px;
  font-style: normal;
}

.footer__row {
  display: flex;
  align-items: baseline;
  gap: 10px;
  font-size: 14px;
  line-height: 1.65;
  color: rgba(242, 247, 248, 0.78);
}

.footer__key {
  flex: none;
  width: 34px;
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.14em;
  color: var(--c-steel);
}

.footer__val { word-break: break-word; }

.footer__note {
  margin-top: 14px;
  padding-left: 11px;
  border-left: 1px solid rgba(255, 91, 31, 0.5);
  font-size: 12.5px;
  line-height: 1.7;
  color: var(--c-steel);
}

.footer__bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 24px;
  margin-top: clamp(32px, 5vw, 52px);
  padding-top: 18px;
  border-top: 1px solid var(--c-line);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--c-steel);
}

.footer__copy,
.footer__icp { line-height: 1.6; }

/* ---------- 8. 通用标题与章节 ---------- */
.eyebrow {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.28em;
  text-transform: uppercase;
  color: var(--c-cyan);
}

.chapter {
  position: relative;
  padding-block: clamp(32px, 5vw, 56px);
}

.chapter__num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(3.5rem, 12vw, var(--fs-120));
  font-weight: 700;
  line-height: 0.82;
  letter-spacing: -0.05em;
  color: rgba(38, 240, 224, 0.16);
  -webkit-text-stroke: 1px rgba(38, 240, 224, 0.42);
}

.chapter__label {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.26em;
  color: var(--c-steel);
  text-transform: uppercase;
}

.chapter__label::before {
  content: "";
  width: 26px;
  height: 1px;
  background: var(--c-cyan);
}

/* ---------- 9. 按钮与标签 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 13px 22px;
  font-size: 15px;
  font-weight: 700;
  line-height: 1.35;
  letter-spacing: 0.04em;
  color: var(--c-white);
  background: var(--c-glass);
  border: 1px solid var(--c-line);
  clip-path: polygon(0 0, 100% 0, 100% 74%, calc(100% - 15px) 100%, 0 100%);
  transition: transform 0.22s var(--ease), background 0.22s var(--ease),
    border-color 0.22s var(--ease), color 0.22s var(--ease), box-shadow 0.22s var(--ease);
}

.btn:hover {
  transform: translateY(-2px);
  color: var(--c-cyan);
  border-color: var(--c-cyan);
  box-shadow: 0 14px 34px -22px rgba(38, 240, 224, 0.9);
}

.btn--primary {
  color: var(--c-ink);
  background: linear-gradient(135deg, var(--c-orange) 0%, var(--c-orange-glow) 100%);
  border-color: transparent;
  box-shadow: 0 16px 36px -18px rgba(255, 91, 31, 0.95);
}

.btn--primary:hover {
  color: var(--c-ink);
  filter: brightness(1.07);
  border-color: transparent;
  box-shadow: 0 20px 44px -18px rgba(255, 138, 77, 0.95);
}

.btn--ghost { background: transparent; }

.tag {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 4px 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--c-cyan);
  background: rgba(38, 240, 224, 0.1);
  border: 1px solid rgba(38, 240, 224, 0.34);
  border-radius: 2px;
}

.tag--accent {
  color: var(--c-orange-glow);
  background: rgba(255, 91, 31, 0.12);
  border-color: rgba(255, 91, 31, 0.42);
}

/* ---------- 10. 面板 / 网格 / 正文 ---------- */
.panel {
  position: relative;
  padding: clamp(18px, 2.4vw, 26px);
  background: linear-gradient(160deg, var(--c-glass) 0%, var(--c-glass-2) 100%);
  border: 1px solid var(--c-line);
  border-radius: 3px;
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
  transition: border-color 0.24s var(--ease), transform 0.24s var(--ease),
    box-shadow 0.24s var(--ease);
}

.panel::after {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  width: 22px;
  height: 22px;
  border-top: 1px solid rgba(38, 240, 224, 0.55);
  border-right: 1px solid rgba(38, 240, 224, 0.55);
  pointer-events: none;
}

.panel:hover {
  transform: translateY(-3px);
  border-color: rgba(38, 240, 224, 0.45);
  box-shadow: 0 22px 50px -30px rgba(38, 240, 224, 0.75);
}

.grid {
  display: grid;
  gap: 18px;
  grid-template-columns: 1fr;
}

.prose {
  max-width: 68ch;
  font-size: 1.0625rem;
  line-height: 1.82;
  color: rgba(242, 247, 248, 0.82);
}

.prose > * + * { margin-top: 1.05em; }
.prose h2 { margin-top: 1.9em; color: var(--c-white); }
.prose h3 { margin-top: 1.6em; color: var(--c-white); }
.prose a { color: var(--c-cyan); border-bottom: 1px solid rgba(38, 240, 224, 0.4); }
.prose a:hover { border-bottom-color: var(--c-cyan); }
.prose ul, .prose ol { padding-left: 1.25em; }
.prose ul li { list-style: none; position: relative; }
.prose ul li::before {
  content: "";
  position: absolute;
  left: -1em;
  top: 0.78em;
  width: 5px;
  height: 5px;
  background: var(--c-orange);
  transform: rotate(45deg);
}
.prose ol { list-style: decimal; }
.prose blockquote {
  padding: 4px 0 4px 18px;
  border-left: 2px solid var(--c-cyan);
  color: var(--c-steel);
}

/* ---------- 11. 面包屑 ---------- */
.breadcrumbs {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--c-steel);
}

.breadcrumbs ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

.breadcrumbs li { display: inline-flex; align-items: center; }

.breadcrumbs li + li::before {
  content: "›";
  margin-right: 8px;
  color: #2C5560;
}

.breadcrumbs a { color: var(--c-steel); transition: color 0.2s var(--ease); }
.breadcrumbs a:hover { color: var(--c-cyan); }
.breadcrumbs [aria-current="page"] { color: var(--c-white); }

/* ---------- 12. 图片容器（页面阶段放占位图） ---------- */
.media {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--c-line);
  border-radius: 3px;
  background-color: #080D13;
  background-image:
    repeating-linear-gradient(135deg, rgba(38, 240, 224, 0.055) 0 1px, transparent 1px 14px),
    linear-gradient(160deg, #101B24 0%, #080D13 72%);
  isolation: isolate;
}

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

.media::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(200deg, rgba(38, 240, 224, 0.1), transparent 46%, rgba(255, 91, 31, 0.07));
  pointer-events: none;
}

.media--16x9 { aspect-ratio: 16 / 9; }
.media--4x3 { aspect-ratio: 4 / 3; }
.media--1x1 { aspect-ratio: 1 / 1; }
.media--21x9 { aspect-ratio: 21 / 9; }

.media__label {
  position: absolute;
  left: 12px;
  bottom: 12px;
  z-index: 2;
  padding: 4px 9px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--c-cyan);
  background: rgba(7, 11, 16, 0.74);
  border: 1px solid rgba(38, 240, 224, 0.3);
  border-radius: 2px;
}

/* ---------- 13. 仪表块与检索胶囊 ---------- */
.stat {
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.stat__value {
  font-family: var(--font-mono);
  font-size: clamp(1.55rem, 4vw, 2.4rem);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--c-cyan);
}

.stat__key {
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--c-steel);
  text-transform: uppercase;
}

.search-capsule {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  padding: 11px 18px;
  font-size: 14px;
  color: var(--c-steel);
  background: rgba(242, 247, 248, 0.06);
  border: 1px solid var(--c-line);
  border-radius: 999px;
  transition: border-color 0.22s var(--ease), box-shadow 0.22s var(--ease),
    color 0.22s var(--ease);
}

.search-capsule::before {
  content: "";
  flex: none;
  width: 11px;
  height: 11px;
  border: 2px solid var(--c-cyan);
  border-radius: 50%;
}

.search-capsule:hover {
  color: var(--c-white);
  border-color: var(--c-cyan);
  box-shadow: 0 0 0 4px rgba(38, 240, 224, 0.08);
}

/* ---------- 14. 进度条 / 显现 / 目录高亮 ---------- */
.read-progress {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 130;
  height: 3px;
  background: linear-gradient(90deg, var(--c-cyan), var(--c-orange));
  transform: scaleX(var(--p, 0));
  transform-origin: 0 50%;
  pointer-events: none;
  will-change: transform;
}

.js [data-reveal] {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 0.55s var(--ease), transform 0.55s var(--ease);
}

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

[data-toc-link].is-active {
  color: var(--c-cyan);
  border-color: var(--c-cyan);
}

/* ---------- 15. 断点 ---------- */
@media (min-width: 560px) {
  :root { --gutter: 26px; }
  .grid--2,
  .grid--3,
  .grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer__top { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 36px 32px; }
  .footer__brand { grid-column: 1 / -1; }
}

@media (min-width: 768px) {
  :root { --gutter: 34px; }
  .site-header { padding-inline: 22px; }
  .nav__link { font-size: 16px; }
  .brand__name { font-size: 16px; }
}

@media (min-width: 1024px) {
  :root { --gutter: 44px; }

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

  .site-header {
    top: 0;
    bottom: 0;
    right: auto;
    width: var(--rail-w);
    height: auto;
    flex-direction: column;
    align-items: center;
    justify-content: flex-start;
    gap: 0;
    padding: 22px 0 18px;
    border-bottom: 0;
    border-right: 1px solid var(--c-line);
    background: linear-gradient(180deg, #0B131B 0%, #070B10 46%, #0A121A 100%);
    box-shadow: 24px 0 60px -46px rgba(0, 0, 0, 1);
  }

  .brand {
    flex-direction: column;
    gap: 9px;
    text-align: center;
  }

  .brand__mark { width: 38px; height: 38px; font-size: 19px; }

  .brand__text { align-items: center; }
  .brand__name { font-size: 12.5px; letter-spacing: 0.1em; }
  .brand__sub { font-size: 9px; letter-spacing: 0.2em; }

  .nav-toggle { display: none; }

  .nav {
    position: static;
    flex: 1 1 auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    width: 100%;
    max-height: none;
    overflow: visible;
    margin: 0;
    padding: 0;
    background: none;
    border: 0;
    box-shadow: none;
    visibility: visible;
    opacity: 1;
    transform: none;
    transition: none;
  }

  .nav__list {
    width: 100%;
    flex-direction: column;
    gap: 2px;
  }

  .nav__item + .nav__item { border-top: 0; }

  .nav__link {
    position: relative;
    flex-direction: column;
    justify-content: center;
    gap: 7px;
    width: 100%;
    padding: 10px 0;
    font-size: 12px;
    letter-spacing: 0.14em;
    text-align: center;
  }

  .nav__link:hover { background: rgba(38, 240, 224, 0.07); }

  .nav__link[aria-current="page"] { background: rgba(38, 240, 224, 0.08); }

  .nav__link[aria-current="page"]::after {
    content: "";
    position: absolute;
    left: 50%;
    bottom: 4px;
    width: 18px;
    height: 1px;
    background: var(--c-orange);
    transform: translateX(-50%);
  }

  .nav__label { font-size: 12px; }

  .nav__cta {
    width: 64px;
    margin-top: 20px;
    padding: 11px 6px;
    font-size: 11.5px;
    line-height: 1.35;
    letter-spacing: 0.08em;
  }

  .read-progress {
    top: 0;
    bottom: 0;
    right: auto;
    left: calc(var(--rail-w) - 3px);
    width: 3px;
    height: auto;
    background: linear-gradient(180deg, var(--c-cyan), var(--c-orange));
    transform: scaleY(var(--p, 0));
    transform-origin: 50% 0;
  }

  .footer__top {
    grid-template-columns: 1.55fr 1fr 1fr 1.35fr;
    gap: 44px 38px;
  }

  .footer__brand { grid-column: auto; }

  .skip-link { left: calc(var(--rail-w) + 14px); }
}

@media (min-width: 1280px) {
  :root { --gutter: 52px; }
  .footer__top { gap: 52px 46px; }
}

/* ---------- 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;
    scroll-behavior: auto !important;
  }

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

  .btn:hover,
  .panel:hover,
  .footer__link:hover,
  .nav__cta:hover { transform: none; }
}