/* ===== 基础 ===== */
:root {
  --primary: #1d4ed8;
  --primary-hover: #1e40af;
  --blue-bg: #eff6ff;
  --ink: #0f172a;
  --text: #475569;
  --muted: #64748b;
  --line: #e2e8f0;
  --white: #ffffff;
  --radius: 8px;
  --radius-lg: 12px;
  --shadow-sm: 0 1px 3px rgba(15, 23, 42, 0.08);
  --container: 1120px;
  --header-h: 64px;
}

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

html { scroll-behavior: smooth; scroll-padding-top: calc(var(--header-h) + 16px); }

body {
  font-family: -apple-system, "Segoe UI", "Microsoft YaHei", "PingFang SC", sans-serif;
  font-size: 16px;
  line-height: 1.7;
  color: var(--text);
  background: var(--white);
  -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; height: auto; display: block; }
a { color: var(--primary); text-decoration: none; }
ul { list-style: none; }

.container { max-width: var(--container); margin: 0 auto; padding: 0 24px; }

.section-title {
  font-size: 32px;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 48px;
}

.btn {
  display: inline-block;
  font-size: 15px;
  font-weight: 600;
  padding: 10px 24px;
  border-radius: var(--radius);
  white-space: nowrap;
  transition: background-color .2s, border-color .2s, color .2s;
}
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-hover); }
.btn-secondary { border: 1px solid #cbd5e1; color: var(--text); background: var(--white); }
.btn-secondary:hover { border-color: var(--primary); color: var(--primary); }
.btn-large { font-size: 17px; padding: 14px 40px; }
.btn-small { font-size: 14px; padding: 8px 18px; }

/* ===== 顶部导航 ===== */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  height: var(--header-h);
  background: transparent;
  transition: background-color .25s, box-shadow .25s;
}
.site-header.scrolled { background: var(--white); box-shadow: var(--shadow-sm); }

.header-inner {
  height: 100%;
  display: flex;
  align-items: center;
  gap: 32px;
}

.logo { font-size: 20px; font-weight: 800; color: var(--ink); letter-spacing: -0.02em; }

.nav { display: flex; gap: 28px; margin-left: auto; }
.nav-link { color: var(--text); font-size: 15px; white-space: nowrap; transition: color .2s; }
.nav-link:hover, .nav-link.active { color: var(--primary); }

/* ===== Hero ===== */
.hero {
  padding: calc(var(--header-h) + 72px) 0 72px;
  background: linear-gradient(180deg, var(--blue-bg) 0%, #fff 100%);
}
.hero-inner { display: flex; align-items: center; gap: 48px; }
.hero-text { flex: 1 1 50%; }
.hero h1 {
  font-size: 46px;
  font-weight: 800;
  line-height: 1.15;
  color: var(--ink);
  margin-bottom: 16px;
}
.hero .accent { color: var(--primary); }
.hero-sub { font-size: 20px; color: var(--ink); margin-bottom: 12px; }
.hero-desc { font-size: 16px; color: var(--muted); margin-bottom: 32px; }
.hero-actions { display: flex; gap: 12px; }
.hero-media { flex: 1 1 50%; }

.window {
  background: var(--white);
  border-radius: var(--radius-lg);
  border: 1px solid var(--line);
  box-shadow: 0 12px 32px rgba(15, 23, 42, 0.12);
  overflow: hidden;
}

/* ===== 数据条 ===== */
.stats { border-bottom: 1px solid var(--line); }
.stats-inner {
  display: flex;
  justify-content: space-between;
  gap: 24px;
  padding: 40px 24px;
}
.stat { text-align: center; flex: 1; }
.stat strong { display: block; font-size: 28px; font-weight: 800; color: var(--primary); }
.stat span { font-size: 14px; color: var(--muted); }

/* ===== 汉堡按钮（基础态隐藏，≤767px 由响应式开启） ===== */
.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: 0;
  cursor: pointer;
  padding: 8px;
  margin-left: auto;
}
.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--ink);
  border-radius: 1px;
}

/* ===== 功能区块 ===== */
.features { padding: 96px 0 0; }
.feature { display: flex; align-items: center; gap: 64px; padding: 48px 0; }
.feature-reverse .feature-media { order: -1; }
.feature-text { flex: 1 1 50%; }
.feature h3 { font-size: 28px; font-weight: 700; color: var(--ink); margin-bottom: 16px; }
.feature-text > p { margin-bottom: 16px; }
.feature-list li { position: relative; padding-left: 24px; margin-bottom: 10px; }
.feature-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 10px;
  width: 8px;
  height: 8px;
  border-radius: 2px;
  background: var(--primary);
}
.feature-media { flex: 1 1 50%; }
.feature-media img {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  background: var(--white);
}

/* ===== 更多功能网格 ===== */
.more { padding: 72px 0 96px; }
.more-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.card {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 24px;
  background: var(--white);
  transition: box-shadow .2s, transform .2s;
}
.card:hover { box-shadow: 0 8px 24px rgba(15, 23, 42, 0.08); transform: translateY(-2px); }
.card-icon {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--blue-bg);
  color: var(--primary);
  border-radius: var(--radius);
  font-size: 20px;
  margin-bottom: 12px;
}
.card h3 { font-size: 17px; color: var(--ink); margin-bottom: 6px; }
.card p { font-size: 14px; color: var(--muted); }

/* ===== 下载区 ===== */
.download { padding: 88px 0; background: var(--blue-bg); text-align: center; }
.download h2 { font-size: 32px; font-weight: 700; color: var(--ink); margin-bottom: 12px; }
.download-meta { color: var(--muted); margin-bottom: 28px; }
.download-note { margin-top: 16px; font-size: 14px; color: var(--muted); }
.download-links {
  margin-top: 24px;
  font-size: 14px;
  display: flex;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
}
.download-links .sep { color: #cbd5e1; }

/* ===== 技术支持 ===== */
.support { padding: 96px 0; }
.support-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 20px; }
.support-item {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 24px;
  min-width: 0;
  overflow-wrap: anywhere;
}
.support-item h3 { font-size: 14px; color: var(--muted); margin-bottom: 8px; font-weight: 600; }
.support-item p { color: var(--ink); font-weight: 600; }

/* ===== 页脚 ===== */
.site-footer { background: var(--ink); color: #94a3b8; padding: 32px 0; }
.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}
.footer-inner p { font-size: 14px; }
.footer-links { display: flex; gap: 20px; flex-wrap: wrap; }
.footer-links a { color: #94a3b8; font-size: 14px; }
.footer-links a:hover { color: #fff; }

/* ===== 滚动渐显（仅 JS 可用时隐藏；用独立 translate 属性，不占用 transform） ===== */
.js .feature, .js .card, .js .support-item, .js .stat {
  opacity: 0;
  translate: 0 24px;
  transition: opacity .6s ease, translate .6s ease;
}
/* 卡片保留自身 hover 过渡（box-shadow/transform 不被渐显动画覆盖） */
.js .card {
  transition: opacity .6s ease, translate .6s ease, box-shadow .2s, transform .2s;
}
.js .feature.revealed, .js .card.revealed, .js .support-item.revealed, .js .stat.revealed {
  opacity: 1;
  translate: none;
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .js .feature, .js .card, .js .support-item, .js .stat { opacity: 1; translate: none; transition: none; }
}
/* 打印时全部显示（未滚到视口的渐显元素不印空白） */
@media print {
  .js .feature, .js .card, .js .support-item, .js .stat { opacity: 1; translate: none; }
}

/* ===== 响应式 ===== */
@media (max-width: 1023px) {
  .hero-inner { flex-direction: column; }
  .hero h1 { font-size: 36px; }
  .feature { flex-direction: column; gap: 32px; }
  .feature-reverse .feature-media { order: 0; }
  .more-grid { grid-template-columns: repeat(2, 1fr); }
  .support-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .section-title { font-size: 28px; }
}

@media (max-width: 767px) {
  /* 汉堡按钮仅 JS 可用时出现（无 JS 时点了没反应，是僵尸按钮） */
  .js .nav-toggle { display: flex; }
  /* 渐进增强：仅 JS 可用时隐藏桌面导航，无 JS 的移动端仍能看到链接 */
  .js .nav, .js .site-header .btn { display: none; }
  .nav.open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: var(--header-h);
    left: 0;
    right: 0;
    background: var(--white);
    box-shadow: var(--shadow-sm);
    padding: 16px 24px;
    gap: 16px;
    margin-left: 0;
  }
  .hero { padding-top: calc(var(--header-h) + 48px); }
  .stats-inner { flex-wrap: wrap; padding: 28px 24px; }
  .stat { flex: 1 1 40%; }
  .more-grid { grid-template-columns: 1fr; }
  .support-grid { grid-template-columns: 1fr; }
  .more, .support, .download { padding-top: 64px; padding-bottom: 64px; }
  .features { padding-top: 64px; padding-bottom: 0; }
}