/* ============================================================
   九紫木兰 · 官网设计系统 v2 (UX Pro Max 优化版)
   品牌色保持不变，增强可访问性/触控/性能/微交互
   ============================================================ */

:root {
  /* —— 品牌色（保持） —— */
  --purple: #3B1E5E;
  --purple-deep: #241039;
  --purple-light: #5A3A8C;
  --gold: #C9A063;
  --gold-soft: #E0C89A;
  --gold-dark: #A87F44;
  --ivory: #F7F3EC;
  --ink: #1A1A1A;
  --warm-gray: #8C8378;
  --line: rgba(36, 16, 57, 0.12);

  /* —— 可访问性增强：确保对比度 ≥ 4.5:1 —— */
  --text-primary: #1A1A1A;
  --text-secondary: #4A4A4A;
  --text-on-purple: #FFFFFF;
  --focus-ring: #C9A063;
  --error: #C53030;
  --success: #38A169;

  /* —— 阴影层次（更精致） —— */
  --shadow-sm: 0 2px 8px rgba(36, 16, 57, 0.06);
  --shadow-md: 0 8px 24px rgba(36, 16, 57, 0.08);
  --shadow-lg: 0 16px 40px rgba(36, 16, 57, 0.12);
  --shadow-xl: 0 24px 60px rgba(36, 16, 57, 0.16);
  --shadow-focus: 0 0 0 3px rgba(201, 160, 99, 0.4);

  /* —— 圆角 —— */
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-pill: 999px;

  /* —— 布局 —— */
  --content-max: 1200px;
  --gutter: 16px;
  --touch-target: 44px; /* iOS/Android 最小触控目标 */

  /* —— 字体 —— */
  --font-serif: "Noto Serif SC", "Source Han Serif SC", "Songti SC", serif;
  --font-sans: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "HarmonyOS Sans", -apple-system, BlinkMacSystemFont, sans-serif;

  /* —— 过渡/动效 —— */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);
  --ease-in-out: cubic-bezier(0.4, 0, 0.2, 1);
  --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
}

/* ============================================================
   基础样式
   ============================================================ */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

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

body {
  font-family: var(--font-sans);
  color: var(--text-primary);
  background: var(--ivory);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
  min-height: 100vh;
}

/* —— 字体优化：减少布局偏移 —— */
@font-face {
  font-family: 'Noto Serif SC';
  font-display: swap;
  src: local('Noto Serif SC');
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-serif);
  line-height: 1.3;
  font-weight: 600;
  color: var(--purple-deep);
}

a {
  color: inherit;
  text-decoration: none;
  transition: color var(--transition-fast);
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* —— 懒加载图片：模糊到清晰 —— */
img[loading="lazy"] {
  filter: blur(8px);
  transition: filter var(--transition-slow);
}
img[loading="lazy"].loaded {
  filter: blur(0);
}

.container {
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 0 max(var(--gutter), env(safe-area-inset-left));
}

/* ============================================================
   可访问性（CRITICAL）
   ============================================================ */

/* 焦点环：键盘导航可见，鼠标点击不显示 */
:focus {
  outline: 2px solid var(--focus-ring);
  outline-offset: 2px;
}
:focus:not(:focus-visible) {
  outline: none;
}
:focus-visible {
  outline: 3px solid var(--focus-ring);
  outline-offset: 3px;
}

/* 跳到主内容（屏幕阅读器） */
.skip-to-content {
  position: absolute;
  top: -100px;
  left: 0;
  background: var(--purple);
  color: #fff;
  padding: 12px 24px;
  z-index: 1000;
  transition: top var(--transition-fast);
}
.skip-to-content:focus {
  top: 0;
}

/* 减少动画（用户偏好） */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  html { scroll-behavior: auto; }
}

/* 高对比度模式 */
@media (prefers-contrast: high) {
  :root {
    --purple: #2A0F45;
    --gold: #B38F4D;
  }
}

/* ============================================================
   占位图（保持品牌渐变）
   ============================================================ */
.ph {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  color: rgba(255, 255, 255, 0.9);
  font-size: 13px;
  letter-spacing: 1px;
  background: linear-gradient(135deg, var(--purple) 0%, var(--purple-deep) 100%);
  border-radius: var(--radius-md);
  overflow: hidden;
  min-height: 200px;
}
.ph::after {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at 30% 20%, rgba(201,160,99,0.35), transparent 55%);
  pointer-events: none;
}
.ph span {
  position: relative;
  z-index: 1;
  padding: 12px;
}
.ph--gold {
  background: linear-gradient(135deg, var(--gold) 0%, var(--gold-dark) 100%);
}
.ph--ivory {
  background: linear-gradient(135deg, #efe7d8 0%, #d9ccb4 100%);
  color: var(--purple);
}

/* ============================================================
   导航（增强触控/可访问性）
   ============================================================ */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  transition: background var(--transition-base), box-shadow var(--transition-base);
}
.site-header.scrolled {
  background: rgba(36, 16, 57, 0.94);
  backdrop-filter: blur(12px) saturate(180%);
  -webkit-backdrop-filter: blur(12px) saturate(180%);
  box-shadow: var(--shadow-md);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 72px;
  padding: 12px 0;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  color: #fff;
  /* 触控目标 ≥ 44px */
  min-height: var(--touch-target);
  padding: 8px 0;
}
.brand .mark {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--gold), var(--gold-soft));
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--purple-deep);
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: 20px;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}
.brand:hover .mark {
  transform: scale(1.05);
  box-shadow: var(--shadow-md);
}
.brand b {
  font-family: var(--font-serif);
  font-size: 22px;
  letter-spacing: 2px;
  font-weight: 600;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
  list-style: none;
}
.nav-links a {
  color: rgba(255,255,255,.88);
  font-size: 15px;
  position: relative;
  /* 触控目标 */
  padding: 12px 4px;
  transition: color var(--transition-fast);
}
.nav-links a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 8px;
  width: 0;
  height: 2px;
  background: var(--gold);
  transition: width var(--transition-base) var(--ease-spring);
}
.nav-links a:hover,
.nav-links a.active {
  color: #fff;
}
.nav-links a:hover::after,
.nav-links a.active::after {
  width: 100%;
}

.nav-cta {
  display: flex;
  align-items: center;
  gap: 12px;
}

/* 汉堡菜单（触控目标 ≥ 44px） */
.burger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 44px;
  height: 44px;
  cursor: pointer;
  background: transparent;
  border: none;
  padding: 10px;
  transition: transform var(--transition-fast);
}
.burger:active {
  transform: scale(0.95);
}
.burger span {
  width: 24px;
  height: 2px;
  background: #fff;
  transition: transform var(--transition-base), opacity var(--transition-fast);
  border-radius: 2px;
}
.burger.open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.burger.open span:nth-child(2) {
  opacity: 0;
}
.burger.open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ============================================================
   按钮（触控优化 + 加载状态）
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  /* 触控目标 ≥ 44px */
  min-height: var(--touch-target);
  padding: 12px 32px;
  border-radius: var(--radius-md);
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  border: 2px solid transparent;
  transition: all var(--transition-base) var(--ease-in-out);
  white-space: nowrap;
  position: relative;
  overflow: hidden;
  user-select: none;
}
.btn::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at center, rgba(255,255,255,0.2), transparent 70%);
  opacity: 0;
  transition: opacity var(--transition-fast);
}
.btn:hover::before {
  opacity: 1;
}
.btn:active {
  transform: scale(0.97);
}

/* 主按钮 */
.btn-primary {
  background: linear-gradient(135deg, var(--gold), var(--gold-soft));
  color: var(--purple-deep);
  box-shadow: var(--shadow-sm);
}
.btn-primary:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

/* 幽灵按钮 */
.btn-ghost {
  border-color: rgba(255,255,255,.6);
  color: #fff;
  background: transparent;
}
.btn-ghost:hover {
  background: rgba(255,255,255,0.12);
  border-color: #fff;
}

/* 描边按钮 */
.btn-outline {
  border-color: var(--purple);
  color: var(--purple);
  background: transparent;
}
.btn-outline:hover {
  background: var(--purple);
  color: #fff;
}

/* 尺寸变体 */
.btn-sm {
  min-height: 36px;
  padding: 8px 20px;
  font-size: 14px;
}
.btn-lg {
  min-height: 52px;
  padding: 16px 40px;
  font-size: 17px;
}

/* 加载状态 */
.btn:disabled,
.btn.loading {
  opacity: 0.6;
  cursor: not-allowed;
  pointer-events: none;
}
.btn.loading::after {
  content: "";
  width: 16px;
  height: 16px;
  border: 2px solid currentColor;
  border-top-color: transparent;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin-left: 8px;
}
@keyframes spin {
  to { transform: rotate(360deg); }
}

/* ============================================================
   通用区块 / 标题
   ============================================================ */
section {
  position: relative;
}
.section-pad {
  padding: 96px 0;
}
@media (max-width: 768px) {
  .section-pad { padding: 64px 0; }
}

.section-head {
  text-align: center;
  max-width: 720px;
  margin: 0 auto 64px;
}
.eyebrow {
  display: inline-block;
  color: var(--gold);
  font-size: 13px;
  letter-spacing: 4px;
  text-transform: uppercase;
  margin-bottom: 16px;
  font-weight: 700;
}
.section-head h2 {
  font-size: clamp(28px, 5vw, 42px);
  color: var(--purple-deep);
  margin-bottom: 16px;
}
.section-head p {
  color: var(--text-secondary);
  font-size: 17px;
  line-height: 1.8;
}

.bg-ivory { background: var(--ivory); }
.bg-purple {
  background: linear-gradient(135deg, var(--purple) 0%, var(--purple-deep) 100%);
  color: #fff;
}
.bg-purple .section-head h2,
.bg-purple h1, .bg-purple h2, .bg-purple h3 {
  color: #fff;
}
.bg-purple .section-head p {
  color: rgba(255,255,255,.85);
}

/* ============================================================
   Hero（增强视觉层次与动效）
   ============================================================ */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  position: relative;
  color: #fff;
  overflow: hidden;
  background: linear-gradient(135deg, var(--purple) 0%, var(--purple-deep) 70%);
  padding-top: 72px; /* 导航高度 */
}
.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at 78% 25%, rgba(201,160,99,.32), transparent 45%),
    radial-gradient(circle at 12% 80%, rgba(201,160,99,.16), transparent 40%);
  animation: gradient-shift 20s ease-in-out infinite alternate;
}
@keyframes gradient-shift {
  to {
    transform: scale(1.1) rotate(5deg);
  }
}

.hero-petal {
  position: absolute;
  right: -80px;
  top: 50%;
  transform: translateY(-50%);
  width: 600px;
  height: 600px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(201,160,99,.28), transparent 65%);
  filter: blur(60px);
  animation: float 15s ease-in-out infinite;
}
@keyframes float {
  0%, 100% { transform: translateY(-50%) translateX(0); }
  50% { transform: translateY(-45%) translateX(-30px); }
}

.hero-inner {
  position: relative;
  z-index: 2;
  max-width: 760px;
  animation: fade-in-up 1s var(--ease-spring) 0.2s both;
}
@keyframes fade-in-up {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.hero h1 {
  font-size: clamp(38px, 8vw, 68px);
  letter-spacing: 4px;
  margin-bottom: 12px;
  color: #fff;
  text-shadow: 0 4px 20px rgba(0,0,0,0.3);
}
.hero .sub {
  font-size: clamp(18px, 3vw, 24px);
  color: var(--gold-soft);
  font-family: var(--font-serif);
  margin-bottom: 28px;
  letter-spacing: 1px;
}
.hero .desc {
  font-size: 17px;
  color: rgba(255,255,255,.88);
  max-width: 580px;
  margin-bottom: 48px;
  line-height: 1.8;
}
.hero-actions {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

/* ============================================================
   卡片系统（增强阴影与悬浮）
   ============================================================ */
.card {
  background: #fff;
  border-radius: var(--radius-lg);
  padding: 36px;
  box-shadow: var(--shadow-md);
  transition: transform var(--transition-base) var(--ease-spring),
              box-shadow var(--transition-base);
  border: 1px solid rgba(59, 30, 94, 0.06);
}
.card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-xl);
}

.card-icon {
  width: 64px;
  height: 64px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--gold), var(--gold-soft));
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 30px;
  margin-bottom: 24px;
  box-shadow: var(--shadow-sm);
}
.card-icon svg {
  width: 32px;
  height: 32px;
  stroke: var(--purple-deep);
  stroke-width: 2.5;
}
.card h3 {
  font-size: 22px;
  color: var(--purple-deep);
  margin-bottom: 12px;
}
.card p {
  color: var(--text-secondary);
  font-size: 15px;
  line-height: 1.7;
}

.grid {
  display: grid;
  gap: 32px;
}
.grid-2 {
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 300px), 1fr));
}
.grid-3 {
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 280px), 1fr));
}
.grid-4 {
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 240px), 1fr));
}

/* ============================================================
   六维模型 / 产品体系
   ============================================================ */
.six-model {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 200px), 1fr));
  gap: 24px;
}
.six-card {
  background: #fff;
  border-radius: var(--radius-lg);
  padding: 32px 24px;
  text-align: center;
  border: 2px solid transparent;
  transition: all var(--transition-base) var(--ease-spring);
  box-shadow: var(--shadow-sm);
}
.six-card:hover {
  border-color: var(--gold);
  transform: translateY(-4px) scale(1.02);
  box-shadow: var(--shadow-lg);
}
.six-card .icon {
  font-size: 48px;
  margin-bottom: 20px;
  filter: drop-shadow(0 2px 8px rgba(201,160,99,0.3));
}
.six-card .icon svg {
  width: 48px;
  height: 48px;
  stroke: var(--gold);
  stroke-width: 2;
}
.six-card .label {
  font-size: 20px;
  font-weight: 700;
  color: var(--purple);
  margin-bottom: 10px;
}
.six-card .desc {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* ============================================================
   会员卡对比表
   ============================================================ */
.membership-table {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 260px), 1fr));
  gap: 28px;
}
.member-card {
  background: #fff;
  border-radius: var(--radius-xl);
  padding: 40px 32px;
  text-align: center;
  position: relative;
  overflow: hidden;
  box-shadow: var(--shadow-md);
  transition: transform var(--transition-base) var(--ease-spring),
              box-shadow var(--transition-base);
  border: 2px solid rgba(59, 30, 94, 0.08);
}
.member-card:hover {
  transform: scale(1.04);
  box-shadow: var(--shadow-xl);
}
.member-card.featured {
  border-color: var(--gold);
  box-shadow: var(--shadow-lg), 0 0 0 1px var(--gold);
}
.member-card.featured::before {
  content: "推荐";
  position: absolute;
  top: 20px;
  right: -28px;
  background: linear-gradient(135deg, var(--gold), var(--gold-dark));
  color: #fff;
  font-size: 12px;
  font-weight: 700;
  padding: 6px 36px;
  transform: rotate(45deg);
  box-shadow: 0 4px 12px rgba(201,160,99,0.4);
}
.member-card h3 {
  font-size: 24px;
  color: var(--purple-deep);
  margin-bottom: 16px;
}
.member-card .price {
  font-size: 40px;
  font-weight: 800;
  color: var(--gold);
  margin-bottom: 12px;
  font-family: var(--font-serif);
}
.member-card .price small {
  font-size: 18px;
  font-weight: 600;
}
.member-card .tagline {
  color: var(--text-secondary);
  font-size: 14px;
  margin-bottom: 32px;
  min-height: 44px;
  line-height: 1.6;
}
.member-card ul {
  list-style: none;
  text-align: left;
  margin-bottom: 32px;
}
.member-card li {
  padding: 12px 0;
  font-size: 14px;
  color: var(--text-primary);
  border-bottom: 1px solid var(--line);
  display: flex;
  align-items: flex-start;
  gap: 10px;
}
.member-card li::before {
  content: "✓";
  color: var(--gold);
  font-weight: 900;
  font-size: 16px;
  flex-shrink: 0;
}
.member-card .btn {
  width: 100%;
}

/* ============================================================
   FAQ（键盘可访问）
   ============================================================ */
.faq {
  max-width: 800px;
  margin: 0 auto;
}
.faq-item {
  background: #fff;
  border-radius: var(--radius-md);
  margin-bottom: 16px;
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: box-shadow var(--transition-fast);
}
.faq-item:hover {
  box-shadow: var(--shadow-md);
}
.faq-q {
  width: 100%;
  text-align: left;
  padding: 20px 28px;
  background: transparent;
  border: none;
  font-size: 17px;
  font-weight: 700;
  color: var(--purple);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  min-height: var(--touch-target);
  transition: color var(--transition-fast);
}
.faq-q:hover {
  color: var(--purple-deep);
}
.faq-q::after {
  content: "+";
  font-size: 28px;
  font-weight: 400;
  flex-shrink: 0;
  transition: transform var(--transition-base) var(--ease-spring);
}
.faq-item.open .faq-q::after {
  transform: rotate(45deg);
}
.faq-a {
  padding: 0 28px;
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-slow), padding var(--transition-slow);
}
.faq-item.open .faq-a {
  padding: 0 28px 24px;
  max-height: 400px;
}
.faq-a p {
  color: var(--text-secondary);
  font-size: 15px;
  line-height: 1.8;
}

/* ============================================================
   底部悬浮 CTA (移动端)
   ============================================================ */
.float-cta {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 90;
  background: linear-gradient(to right, var(--purple), var(--purple-deep));
  padding: 16px max(var(--gutter), env(safe-area-inset-right)) max(16px, env(safe-area-inset-bottom)) max(var(--gutter), env(safe-area-inset-left));
  display: none;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  box-shadow: 0 -4px 20px rgba(0,0,0,.25);
  backdrop-filter: blur(10px);
}
.float-cta .btn {
  flex: 1;
}

/* ============================================================
   页脚
   ============================================================ */
.site-footer {
  background: var(--purple-deep);
  color: rgba(255,255,255,.8);
  padding: 80px 0 40px;
}
.footer-main {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 56px;
  margin-bottom: 56px;
}
.footer-brand {
  max-width: 360px;
}
.footer-brand .brand {
  margin-bottom: 20px;
}
.footer-brand p {
  font-size: 15px;
  line-height: 1.8;
  margin-bottom: 24px;
  color: rgba(255,255,255,.75);
}
.footer-qr {
  display: flex;
  gap: 16px;
}
.footer-qr .ph {
  width: 90px;
  height: 90px;
  font-size: 12px;
}
.footer-col h4 {
  color: #fff;
  font-size: 17px;
  margin-bottom: 20px;
  font-family: var(--font-sans);
  font-weight: 700;
}
.footer-col ul {
  list-style: none;
}
.footer-col a {
  display: block;
  padding: 8px 0;
  font-size: 14px;
  color: rgba(255,255,255,.7);
  transition: color var(--transition-fast);
}
.footer-col a:hover {
  color: var(--gold);
}
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,.15);
  padding-top: 28px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 13px;
  color: rgba(255,255,255,.6);
}
.footer-bottom a {
  color: var(--gold);
  transition: opacity var(--transition-fast);
}
.footer-bottom a:hover {
  opacity: 0.8;
}

/* ============================================================
   响应式
   ============================================================ */
@media (max-width: 1024px) {
  .hero h1 { font-size: 52px; }
  .footer-main {
    grid-template-columns: 1fr 1fr;
    gap: 40px;
  }
}

@media (max-width: 768px) {
  /* 导航 */
  .nav-links,
  .nav-cta {
    display: none;
  }
  .burger {
    display: flex;
  }
  .float-cta {
    display: flex;
  }

  /* Hero */
  .hero {
    min-height: 90vh;
    padding: 100px 0 60px;
  }
  .hero h1 {
    font-size: 42px;
    letter-spacing: 2px;
  }
  .hero .sub {
    font-size: 20px;
  }
  .hero-petal {
    display: none;
  }

  /* 页脚 */
  .footer-main {
    grid-template-columns: 1fr;
    gap: 32px;
  }
  .footer-bottom {
    flex-direction: column;
    gap: 16px;
    text-align: center;
  }

  /* 容器 */
  .container {
    padding: 0 20px;
  }
}

/* ============================================================
   滚动渐入动画（优化性能：GPU 加速）
   ============================================================ */
.fade-in {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity var(--transition-slow), transform var(--transition-slow) var(--ease-spring);
  will-change: transform, opacity;
}
.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* 交错动画（卡片依次出现） */
.fade-in:nth-child(2) { transition-delay: 100ms; }
.fade-in:nth-child(3) { transition-delay: 200ms; }
.fade-in:nth-child(4) { transition-delay: 300ms; }
.fade-in:nth-child(5) { transition-delay: 400ms; }
.fade-in:nth-child(6) { transition-delay: 500ms; }

/* ============================================================
   实用工具类
   ============================================================ */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

/* 打印样式 */
@media print {
  .site-header,
  .float-cta,
  .burger { display: none !important; }
  body { background: white; color: black; }
}