/* ==========================================================================
   OB体育 — /assets/site.css
   数据赛场 Data Arena：共享样式
   重置 / 变量 / 中文排版 / 头部 / 页脚 / 通用组件 / 响应式 / 动效
   ========================================================================== */

:root {
  --color-navy: #0B1F3B;
  --color-blue: #132E4A;
  --color-orange: #FF6B35;
  --color-green: #4ACF7A;
  --color-silver: #C0C0C0;
  --color-cream: #F7F3E8;
  --color-dark: #1A1A1A;
  --color-white: #FFFFFF;
  --color-line: #2E3F5A;
  --color-line-light: rgba(192, 192, 192, 0.35);

  --font-heading: "Noto Sans SC", "PingFang SC", sans-serif;
  --font-body: "Noto Sans SC", "PingFang SC", sans-serif;
  --font-data: "Roboto Mono", "SF Mono", monospace;

  --fs-hero: clamp(2.5rem, 6vw, 5rem);
  --fs-title: clamp(1.75rem, 3.4vw, 2.75rem);
  --fs-subtitle: 1.25rem;
  --fs-body-lg: 1.125rem;
  --fs-body: 1rem;
  --fs-data: 0.875rem;
  --fs-small: 0.8125rem;

  --space-1: 4px;
  --space-2: 8px;
  --space-3: 16px;
  --space-4: 24px;
  --space-5: 32px;
  --space-6: 48px;
  --space-7: 72px;
  --space-8: 120px;

  --header-height: 72px;
  --content-max: 1280px;
  --content-narrow: 760px;

  --shadow-1: 0 2px 8px rgba(11, 31, 59, 0.12);
  --shadow-2: 0 10px 28px rgba(11, 31, 59, 0.22);

  --transition-fast: 160ms ease;
  --transition-base: 240ms ease;
  --transition-slow: 420ms cubic-bezier(0.22, 1, 0.36, 1);

  --progress: 0%;
}

/* ---------- Reset ---------- */

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
  margin: 0;
  font-family: var(--font-body);
  font-size: var(--fs-body);
  line-height: 1.7;
  color: var(--color-dark);
  background: var(--color-cream);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

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

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

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

ul,
ol {
  list-style: none;
}

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

/* ---------- 基础排版 ---------- */

h1,
h2,
h3,
h4 {
  font-family: var(--font-heading);
  font-weight: 900;
  line-height: 1.25;
  color: inherit;
  margin: 0 0 0.55em;
  letter-spacing: -0.015em;
}

h1 {
  font-size: var(--fs-hero);
}

h2 {
  font-size: var(--fs-title);
}

h3 {
  font-size: clamp(1.25rem, 2vw, 1.5rem);
}

h4 {
  font-size: 1.125rem;
}

p {
  line-height: 1.75;
  margin-bottom: 1.25em;
}

strong,
b {
  font-weight: 700;
}

small {
  font-size: 0.875em;
}

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

:focus {
  outline: none;
}

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

#main-content {
  outline: none;
  scroll-margin-top: calc(var(--header-height) + 12px);
}

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

/* ---------- 容器与网格 ---------- */

.container {
  width: 100%;
  max-width: var(--content-max);
  margin-inline: auto;
  padding-inline: var(--space-4);
}

.text-container {
  max-width: var(--content-narrow);
  margin-inline: auto;
  padding-block: var(--space-6);
  padding-inline: var(--space-4);
}

.grid {
  display: grid;
  gap: var(--space-4);
  grid-template-columns: repeat(12, minmax(0, 1fr));
}

.grid-2 {
  display: grid;
  gap: var(--space-4);
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.grid-3 {
  display: grid;
  gap: var(--space-4);
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.grid-4 {
  display: grid;
  gap: var(--space-4);
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

/* ---------- 头部 ---------- */

.skip-link {
  position: absolute;
  top: -48px;
  left: 16px;
  z-index: 1100;
  padding: 10px 16px;
  background: var(--color-orange);
  color: var(--color-navy);
  font-weight: 700;
  text-decoration: none;
  transition: top var(--transition-base);
}

.skip-link:focus {
  top: 16px;
  outline: 2px solid var(--color-white);
  outline-offset: -2px;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  height: var(--header-height);
  background-color: transparent;
  border-bottom: 1px solid transparent;
  color: var(--color-white);
  transition: background-color var(--transition-base), border-color var(--transition-base), box-shadow var(--transition-base);
}

.site-header::before {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(to bottom, rgba(11, 31, 59, 0.55), rgba(11, 31, 59, 0));
  opacity: 1;
  pointer-events: none;
  transition: opacity var(--transition-base);
}

.site-header.is-scrolled {
  background-color: var(--color-navy);
  border-bottom-color: var(--color-line);
  box-shadow: 0 4px 18px rgba(0, 0, 0, 0.25);
}

.site-header.is-scrolled::before {
  opacity: 0;
}

.header-inner {
  position: relative;
  z-index: 2;
  display: flex;
  align-items: center;
  gap: var(--space-4);
  height: 100%;
  max-width: var(--content-max);
  margin-inline: auto;
  padding-inline: var(--space-4);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
  color: var(--color-white);
  font-size: 1.125rem;
  font-weight: 900;
  line-height: 1;
  letter-spacing: 0.05em;
}

.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  background: var(--color-orange);
  color: var(--color-navy);
  font-family: var(--font-data);
  font-weight: 700;
  font-size: 0.8125rem;
  letter-spacing: 0.02em;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 7px), calc(100% - 7px) 100%, 0 100%);
}

.brand-text {
  white-space: nowrap;
  transition: color var(--transition-base);
}

.brand:hover .brand-text,
.brand:focus-visible .brand-text {
  color: var(--color-orange);
}

.site-nav {
  margin-left: auto;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: 2px;
}

.nav-list a {
  position: relative;
  display: block;
  padding: 10px 14px;
  color: rgba(255, 255, 255, 0.85);
  font-size: 0.9375rem;
  font-weight: 500;
  line-height: 1.2;
  letter-spacing: 0.02em;
  white-space: nowrap;
  transition: color var(--transition-base);
}

.nav-list a::after {
  content: "";
  position: absolute;
  left: 14px;
  right: 14px;
  bottom: 4px;
  height: 2px;
  background: var(--color-orange);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--transition-base);
}

.nav-list a:hover,
.nav-list a:focus-visible {
  color: var(--color-white);
}

.nav-list a:hover::after,
.nav-list a:focus-visible::after {
  transform: scaleX(1);
}

.nav-list a[aria-current="page"] {
  color: var(--color-white);
  font-weight: 700;
}

.nav-list a[aria-current="page"]::after {
  transform: scaleX(1);
}

.header-live {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
  padding: 5px 12px;
  border: 1px solid rgba(74, 207, 122, 0.4);
  background: rgba(74, 207, 122, 0.08);
  font-family: var(--font-data);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: var(--color-green);
  text-transform: uppercase;
  white-space: nowrap;
}

.live-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--color-green);
  animation: live-pulse 2.2s ease-out infinite;
}

.live-text {
  line-height: 1;
}

@keyframes live-pulse {
  0% {
    box-shadow: 0 0 0 0 rgba(74, 207, 122, 0.5);
  }
  70% {
    box-shadow: 0 0 0 6px rgba(74, 207, 122, 0);
  }
  100% {
    box-shadow: 0 0 0 0 rgba(74, 207, 122, 0);
  }
}

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
  width: 44px;
  height: 44px;
  flex-shrink: 0;
  padding: 10px;
  border: 1px solid rgba(255, 255, 255, 0.25);
  background: rgba(11, 31, 59, 0.4);
}

.nav-toggle-bar {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--color-white);
  transition: transform var(--transition-base), opacity var(--transition-base);
}

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

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

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

.scroll-progress {
  position: absolute;
  top: 0;
  left: 0;
  z-index: 3;
  height: 3px;
  width: 100%;
  pointer-events: none;
}

.scroll-progress::before {
  content: "";
  display: block;
  height: 100%;
  width: var(--progress, 0%);
  background: linear-gradient(90deg, var(--color-orange), var(--color-green));
  transition: width 120ms linear;
}

/* ---------- 页脚 ---------- */

.site-footer {
  position: relative;
  background: var(--color-navy);
  color: rgba(255, 255, 255, 0.78);
}

.site-footer::before {
  content: "";
  display: block;
  height: 4px;
  background: linear-gradient(90deg, var(--color-orange) 0 40%, var(--color-green) 40% 45%, var(--color-line) 45% 100%);
}

.footer-lead {
  background: var(--color-blue);
  border-bottom: 1px solid var(--color-line);
}

.footer-lead-inner {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding-block: var(--space-3);
}

.trust-line {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-3);
  margin: 0;
  font-size: 0.9375rem;
  color: rgba(255, 255, 255, 0.9);
}

.footer-top {
  display: grid;
  grid-template-columns: minmax(0, 2.2fr) minmax(0, 1fr) minmax(0, 1fr) minmax(0, 1.6fr);
  gap: var(--space-5);
  padding-block: var(--space-6) var(--space-5);
}

.footer-brand .brand {
  margin-bottom: var(--space-3);
}

.footer-description {
  max-width: 36ch;
  margin-bottom: 0;
  font-size: 0.9375rem;
  color: rgba(255, 255, 255, 0.68);
}

.footer-col {
  min-width: 0;
}

.footer-nav {
  padding-left: var(--space-4);
  border-left: 1px solid var(--color-line);
}

.footer-contact {
  min-width: 0;
}

.footer-heading {
  position: relative;
  margin-bottom: var(--space-3);
  padding-bottom: var(--space-2);
  font-size: 0.9375rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--color-white);
}

.footer-heading::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 28px;
  height: 2px;
  background: var(--color-orange);
}

.footer-links li {
  margin-bottom: 4px;
  color: rgba(255, 255, 255, 0.72);
  font-size: 0.9375rem;
}

.footer-links a {
  display: inline-block;
  padding-block: 4px;
  text-decoration: none;
  transition: color var(--transition-base), padding-left var(--transition-base);
}

.footer-links a:hover,
.footer-links a:focus-visible {
  color: var(--color-orange);
  padding-left: 6px;
}

.footer-contact-list li {
  padding-block: 3px;
}

.footer-contact-list li.footer-address {
  line-height: 1.55;
  padding-top: 6px;
  color: rgba(255, 255, 255, 0.58);
  font-size: 0.875rem;
}

.footer-support {
  margin-top: var(--space-3);
  padding-top: var(--space-2);
  border-top: 1px solid var(--color-line);
  font-family: var(--font-data);
  font-size: var(--fs-small);
  color: var(--color-silver);
}

.footer-bottom {
  border-top: 1px solid var(--color-line);
  background: rgba(11, 31, 59, 0.6);
}

.footer-bottom-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-3);
  padding-block: var(--space-3);
  font-family: var(--font-data);
  font-size: var(--fs-small);
  color: rgba(255, 255, 255, 0.5);
}

.footer-copy,
.footer-note {
  margin: 0;
}

/* ---------- 首屏：hero 与数据面板 ---------- */

.hero {
  position: relative;
  display: flex;
  align-items: center;
  min-height: calc(100vh - var(--header-height));
  margin-top: calc(-1 * var(--header-height));
  padding: calc(var(--header-height) + var(--space-6)) var(--space-4) var(--space-7);
  background:
    radial-gradient(ellipse at 80% 20%, rgba(19, 46, 74, 0.9), transparent 60%),
    var(--color-navy);
  color: var(--color-white);
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--color-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--color-line) 1px, transparent 1px);
  background-size: 56px 56px;
  opacity: 0.35;
}

.hero::after {
  content: "";
  position: absolute;
  top: -20%;
  right: -8%;
  width: min(38vw, 520px);
  height: 140%;
  background: var(--color-orange);
  clip-path: polygon(14% 0, 100% 0, 100% 100%, 0 100%);
  opacity: 0.1;
  pointer-events: none;
}

.hero-inner {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
  gap: var(--space-6);
  align-items: center;
  width: 100%;
  max-width: var(--content-max);
  margin-inline: auto;
}

.field-grid {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(var(--color-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--color-line) 1px, transparent 1px);
  background-size: 56px 56px;
  opacity: 0.5;
}

.data-panel {
  position: relative;
  padding: var(--space-4);
  background: rgba(19, 46, 74, 0.72);
  border: 1px solid var(--color-line);
  box-shadow: var(--shadow-2);
}

.data-panel::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  bottom: 0;
  width: 4px;
  background: var(--color-orange);
}

.data-panel-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  margin-bottom: var(--space-3);
  padding-bottom: var(--space-2);
  border-bottom: 1px solid var(--color-line);
}

.data-panel-title {
  font-family: var(--font-data);
  font-size: var(--fs-small);
  font-weight: 700;
  letter-spacing: 0.12em;
  color: var(--color-silver);
  text-transform: uppercase;
}

.data-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-3);
  padding-block: var(--space-2);
  border-bottom: 1px solid var(--color-line);
  font-family: var(--font-data);
  font-size: var(--fs-data);
}

.data-row:last-child {
  border-bottom: 0;
}

.data-row-label {
  color: var(--color-silver);
}

.data-row-value {
  color: var(--color-white);
  font-size: 1rem;
  font-weight: 700;
}

.data-row-value strong {
  color: var(--color-orange);
}

/* ---------- 章节体系 ---------- */

.section {
  padding-block: var(--space-7);
}

.section-dark {
  background: var(--color-navy);
  color: var(--color-white);
}

.section-dark .section-title {
  color: var(--color-white);
}

.section-dark .section-desc {
  color: var(--color-silver);
}

.section-header {
  max-width: var(--content-narrow);
  margin-bottom: var(--space-5);
}

.section-index {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: var(--space-3);
  font-family: var(--font-data);
  font-size: var(--fs-data);
  font-weight: 700;
  letter-spacing: 0.16em;
  color: var(--color-orange);
  text-transform: uppercase;
}

.section-index::before {
  content: "//";
  color: var(--color-silver);
  font-size: 1.05em;
}

.section-index::after {
  content: "";
  display: block;
  width: 40px;
  height: 2px;
  background: currentColor;
}

.section-title {
  color: var(--color-dark);
}

.section-desc {
  max-width: 60ch;
  font-size: var(--fs-subtitle);
  color: var(--color-line);
}

/* ---------- 按钮 ---------- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 10px 22px;
  border: 2px solid transparent;
  background: transparent;
  color: var(--color-white);
  font-family: var(--font-heading);
  font-size: 0.9375rem;
  font-weight: 700;
  letter-spacing: 0.03em;
  text-decoration: none;
  cursor: pointer;
  transition: background var(--transition-base), color var(--transition-base), border-color var(--transition-base), transform var(--transition-base), box-shadow var(--transition-base);
}

.btn:hover,
.btn:focus-visible {
  transform: translateY(-2px);
}

.btn-primary {
  background: var(--color-orange);
  color: var(--color-navy);
}

.btn-primary:hover,
.btn-primary:focus-visible {
  background: #FF8A5C;
  box-shadow: 0 6px 18px rgba(255, 107, 53, 0.35);
}

.btn-outline {
  border-color: var(--color-silver);
  color: var(--color-white);
}

.btn-outline:hover,
.btn-outline:focus-visible {
  border-color: var(--color-orange);
  color: var(--color-orange);
}

.btn-mono {
  font-family: var(--font-data);
  letter-spacing: 0.06em;
}

/* ---------- 面包屑 ---------- */

.breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  padding-block: var(--space-3);
  font-family: var(--font-data);
  font-size: var(--fs-small);
  color: var(--color-silver);
}

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

.breadcrumbs a {
  color: rgba(255, 255, 255, 0.72);
}

.breadcrumbs a:hover,
.breadcrumbs a:focus-visible {
  color: var(--color-orange);
}

.breadcrumbs li + li::before {
  content: "/";
  margin-right: 8px;
  color: var(--color-line);
}

.breadcrumbs [aria-current="page"] {
  color: var(--color-orange);
  font-weight: 700;
}

/* ---------- 卡片、标签、分隔线 ---------- */

.card {
  padding: var(--space-4);
  background: var(--color-white);
  border: 1px solid var(--color-line-light);
  box-shadow: var(--shadow-1);
}

.card-dark {
  padding: var(--space-4);
  background: var(--color-blue);
  border: 1px solid var(--color-line);
  color: var(--color-white);
}

.tag {
  display: inline-block;
  padding: 3px 10px;
  border-left: 2px solid var(--color-orange);
  background: rgba(255, 107, 53, 0.1);
  color: var(--color-orange);
  font-size: var(--fs-small);
  font-weight: 700;
}

.tag-green {
  border-left-color: var(--color-green);
  background: rgba(74, 207, 122, 0.1);
  color: var(--color-green);
}

.data-chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 10px;
  border: 1px solid var(--color-line);
  font-family: var(--font-data);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  line-height: 1.45;
  color: var(--color-silver);
  white-space: nowrap;
}

.divider {
  height: 1px;
  margin: var(--space-6) 0;
  border: 0;
  background: var(--color-line-light);
}

.divider-strong {
  height: 3px;
  margin: var(--space-5) 0;
  border: 0;
  background: var(--color-orange);
}

/* ---------- 步骤节点：技能树 ---------- */

.steps {
  display: grid;
  gap: var(--space-3);
}

.step {
  position: relative;
  display: grid;
  grid-template-columns: 72px 1fr;
  gap: var(--space-3);
  padding: var(--space-3);
  background: var(--color-white);
  border: 1px solid var(--color-line-light);
  color: var(--color-dark);
}

.step::before {
  content: "";
  position: absolute;
  top: 100%;
  left: 36px;
  width: 1px;
  height: var(--space-3);
  background: var(--color-line-light);
}

.step:last-child::before {
  display: none;
}

.step-index {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 56px;
  height: 56px;
  border: 1px solid var(--color-orange);
  background: rgba(255, 107, 53, 0.06);
  color: var(--color-orange);
  font-family: var(--font-data);
  font-size: 1.25rem;
  font-weight: 700;
}

.step-title {
  margin-bottom: 4px;
  color: var(--color-dark);
  font-size: 1.25rem;
  font-weight: 900;
}

.step-body {
  color: var(--color-line);
  font-size: var(--fs-body);
}

/* ---------- 媒体与图片容器 ---------- */

.media-frame {
  position: relative;
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background: var(--color-blue);
  border: 1px solid var(--color-line);
}

.media-frame::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--color-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--color-line) 1px, transparent 1px);
  background-size: 28px 28px;
  opacity: 0.35;
}

.media-frame img,
.media-frame picture,
.media-frame video {
  position: relative;
  z-index: 1;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.media-frame-wide {
  aspect-ratio: 21 / 9;
}

.media-frame-square {
  aspect-ratio: 1 / 1;
}

.media-frame-portrait {
  aspect-ratio: 3 / 4;
}

.media-frame-caption {
  padding-top: var(--space-2);
  font-family: var(--font-data);
  font-size: var(--fs-small);
  color: var(--color-line);
}

/* ---------- 滚动显现 ---------- */

[data-reveal] {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity var(--transition-slow), transform var(--transition-slow);
}

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

/* ---------- 响应式 ---------- */

@media (max-width: 1024px) {
  .grid-3,
  .grid-4 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .footer-top {
    grid-template-columns: 1fr 1fr;
  }

  .footer-brand {
    grid-column: 1 / -1;
  }

  .footer-nav {
    padding-left: 0;
    border-left: 0;
  }
}

@media (max-width: 920px) {
  .hero {
    min-height: auto;
    padding-top: calc(var(--header-height) + var(--space-5));
  }

  .hero-inner {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 860px) {
  .nav-toggle {
    display: flex;
  }

  .site-nav {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    margin-left: 0;
    padding: var(--space-3);
    background: var(--color-navy);
    border-bottom: 3px solid var(--color-orange);
    box-shadow: var(--shadow-2);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: opacity var(--transition-base), transform var(--transition-base), visibility var(--transition-base);
  }

  .site-nav[data-open] {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
  }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }

  .nav-list a {
    padding: 14px 12px;
    border-bottom: 1px solid var(--color-line);
    font-size: 1rem;
  }

  .nav-list a::after {
    display: none;
  }
}

@media (max-width: 640px) {
  .header-live {
    display: none;
  }

  .section {
    padding-block: var(--space-6);
  }

  .grid-2,
  .grid-3,
  .grid-4 {
    grid-template-columns: 1fr;
  }

  .footer-top {
    grid-template-columns: 1fr;
    gap: var(--space-4);
  }

  .footer-brand {
    grid-column: auto;
  }

  .footer-bottom-inner {
    flex-direction: column;
    align-items: flex-start;
  }

  .step {
    grid-template-columns: 56px 1fr;
  }

  .step-index {
    width: 48px;
    height: 48px;
    font-size: 1rem;
  }
}

/* ---------- 减少动态 ---------- */

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    transition-delay: 0s !important;
  }

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