/* ========== 基础重置 ========== */
* { margin: 0; padding: 0; box-sizing: border-box; }
:root {
  --dark: #1a1a1a;
  --blue: #2563eb;
  --blue-dark: #1d4ed8;
  --blue-light: #dbeafe;
  --bg: #ffffff;
  --bg-alt: #f7f8fa;
  --text: #1a1a1a;
  --text-light: #6b7280;
  --border: #e5e7eb;
  --white: #fff;
  --shadow: 0 10px 30px rgba(0,0,0,.08);
  --radius: 16px;
}
html { scroll-behavior: smooth; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Segoe UI", sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  overflow-x: hidden;
}
img { max-width: 100%; display: block; }
a { text-decoration: none; color: inherit; }
.container { max-width: 1180px; margin: 0 auto; padding: 0 24px; }
.container-narrow { max-width: 780px; }

/* ========== 按钮 ========== */
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 12px 26px; border-radius: 10px;
  font-weight: 600; font-size: 15px; cursor: pointer;
  border: none; transition: all .25s ease; white-space: nowrap;
}
.btn-dark {
  background: var(--dark); color: #fff;
  box-shadow: 0 6px 18px rgba(0,0,0,.2);
}
.btn-dark:hover { background: #000; transform: translateY(-2px); }
.btn-blue {
  background: var(--blue); color: #fff;
  box-shadow: 0 6px 18px rgba(37,99,235,.35);
}
.btn-blue:hover { background: var(--blue-dark); transform: translateY(-2px); }
.btn-outline {
  background: transparent; color: var(--dark);
  border: 2px solid var(--border);
}
.btn-outline:hover { border-color: var(--dark); background: var(--bg-alt); }
.btn-lg { padding: 15px 32px; font-size: 16px; }

/* ========== 导航栏 ========== */
.navbar {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  background: rgba(255,255,255,.9); backdrop-filter: blur(12px);
  transition: box-shadow .3s;
}
.navbar.scrolled { box-shadow: 0 2px 16px rgba(0,0,0,.06); }
.nav-inner { display: flex; align-items: center; justify-content: space-between; height: 68px; }
.brand { display: flex; align-items: center; gap: 10px; }
.brand-logo { width: 38px; height: 38px; border-radius: 9px; }
.brand-name { font-size: 20px; font-weight: 800; letter-spacing: 1px; }
.nav-links { display: flex; gap: 32px; }
.nav-links a { font-size: 15px; color: var(--text-light); font-weight: 500; transition: color .2s; }
.nav-links a:hover { color: var(--dark); }
.nav-toggle { display: none; background: none; border: none; cursor: pointer; flex-direction: column; gap: 5px; }
.nav-toggle span { width: 24px; height: 2.5px; background: var(--text); border-radius: 2px; transition: .3s; }

/* ========== Hero ========== */
.hero { padding: 140px 0 80px; background: var(--bg); position: relative; overflow: hidden; }
.hero::before {
  content: ''; position: absolute; top: -200px; right: -200px;
  width: 600px; height: 600px; border-radius: 50%;
  background: radial-gradient(circle, var(--blue-light) 0%, transparent 70%);
}
.hero-inner { position: relative; z-index: 1; display: grid; grid-template-columns: 1fr 1fr; gap: 50px; align-items: center; }
.hero-badge {
  display: inline-block; padding: 6px 16px; border-radius: 999px;
  background: var(--blue-light); color: var(--blue);
  font-size: 13px; font-weight: 600; margin-bottom: 20px;
}
.hero-text h1 { font-size: 60px; line-height: 1.1; font-weight: 900; letter-spacing: 2px; }
.hero-sub { font-size: 20px; color: var(--text-light); margin: 14px 0; font-weight: 500; }
.hero-desc { margin: 0 0 30px; font-size: 16px; color: var(--text-light); max-width: 480px; }
.hero-actions { display: flex; gap: 16px; flex-wrap: wrap; }

/* 手机展示 */
.hero-visual { display: flex; justify-content: center; }
.phone-showcase { position: relative; width: 340px; height: 440px; }
.phone {
  position: absolute; border-radius: 24px; overflow: hidden;
  box-shadow: 0 24px 60px rgba(0,0,0,.15);
  border: 6px solid #fff;
}
.phone img { width: 100%; height: 100%; object-fit: cover; }
.phone-a { width: 200px; height: 400px; left: 0; top: 20px; transform: rotate(-6deg); z-index: 1; }
.phone-b { width: 220px; height: 440px; right: 0; top: 0; z-index: 2; }

/* ========== 数据条 ========== */
.stats { background: var(--dark); color: #fff; padding: 44px 0; }
.stats-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; text-align: center; }
.stat-num { display: block; font-size: 36px; font-weight: 800; }
.stat-label { font-size: 14px; opacity: .7; }

/* ========== 通用 Section ========== */
.section { padding: 90px 0; }
.section-alt { background: var(--bg-alt); }
.section-head { text-align: center; max-width: 600px; margin: 0 auto 50px; }
.section-tag {
  display: inline-block; font-size: 12px; letter-spacing: 4px; font-weight: 700;
  color: var(--blue); margin-bottom: 12px;
}
.section-head h2 { font-size: 36px; font-weight: 800; margin-bottom: 14px; }
.section-head p { color: var(--text-light); font-size: 16px; }

/* ========== 特色卡片 ========== */
.features-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 22px; }
.feature-card {
  background: #fff; padding: 32px 24px; border-radius: var(--radius);
  border: 1px solid var(--border);
  transition: transform .25s, box-shadow .25s;
}
.feature-card:hover { transform: translateY(-6px); box-shadow: var(--shadow); }
.feature-icon {
  width: 54px; height: 54px; border-radius: 14px; font-size: 26px;
  background: var(--bg-alt); display: flex; align-items: center; justify-content: center;
  margin-bottom: 18px;
}
.feature-card h3 { font-size: 18px; margin-bottom: 10px; }
.feature-card p { font-size: 14px; color: var(--text-light); }

/* ========== 界面预览 ========== */
.screens-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; max-width: 880px; margin: 0 auto; }
.screen-shot {
  position: relative; border-radius: 20px; overflow: hidden;
  box-shadow: 0 10px 30px rgba(0,0,0,.1); background: #fff;
  border: 1px solid var(--border);
  transition: transform .3s;
}
.screen-shot:hover { transform: translateY(-6px); }
.screen-shot img { width: 100%; aspect-ratio: 9/16; object-fit: cover; }
.screen-label {
  position: absolute; left: 0; right: 0; bottom: 0;
  padding: 28px 14px 12px; text-align: center;
  background: linear-gradient(transparent, rgba(0,0,0,.6));
  color: #fff; font-size: 14px; font-weight: 600;
}

/* ========== 下载 CTA ========== */
.download-band { background: var(--dark); padding: 90px 0; }
.download-inner { display: flex; justify-content: center; }
.download-card { text-align: center; color: #fff; max-width: 560px; }
.download-icon { width: 88px; height: 88px; border-radius: 20px; margin: 0 auto 22px; box-shadow: 0 10px 30px rgba(0,0,0,.3); }
.download-card h2 { font-size: 36px; margin-bottom: 14px; letter-spacing: 2px; }
.download-card p { opacity: .7; margin-bottom: 26px; font-size: 16px; }
.download-tip { display: block; margin-top: 16px; font-size: 13px; opacity: .5; }

/* ========== FAQ ========== */
.faq-list { display: flex; flex-direction: column; gap: 14px; }
.faq-item {
  background: #fff; border-radius: 12px; overflow: hidden;
  border: 1px solid var(--border);
}
.faq-q {
  width: 100%; text-align: left; background: none; border: none;
  padding: 20px 24px; font-size: 16px; font-weight: 600; cursor: pointer;
  display: flex; justify-content: space-between; align-items: center; color: var(--text);
}
.faq-arrow { transition: transform .3s; font-size: 22px; color: var(--blue); }
.faq-item.open .faq-arrow { transform: rotate(45deg); }
.faq-a { max-height: 0; overflow: hidden; transition: max-height .3s ease; }
.faq-a p { padding: 0 24px 20px; color: var(--text-light); font-size: 15px; }

/* ========== 页脚 ========== */
.footer { background: #111; color: #888; padding: 50px 0 0; }
.footer-inner { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 30px; padding-bottom: 30px; border-bottom: 1px solid rgba(255,255,255,.08); }
.footer-logo { width: 46px; height: 46px; border-radius: 10px; margin-bottom: 12px; }
.footer-brand p { font-size: 14px; max-width: 280px; }
.footer-links { display: flex; gap: 24px; align-items: center; flex-wrap: wrap; }
.footer-links a { font-size: 14px; transition: color .2s; }
.footer-links a:hover { color: #fff; }
.footer-bottom { text-align: center; padding: 20px 0; font-size: 13px; opacity: .7; }

/* ========== 回到顶部 ========== */
.back-top {
  position: fixed; right: 24px; bottom: 24px; width: 46px; height: 46px;
  border-radius: 50%; border: none; cursor: pointer; font-size: 20px;
  background: var(--dark); color: #fff;
  box-shadow: 0 6px 18px rgba(0,0,0,.3);
  opacity: 0; pointer-events: none; transition: .3s; z-index: 99;
}
.back-top.show { opacity: 1; pointer-events: auto; }

/* ========== 响应式 ========== */
@media (max-width: 900px) {
  .hero-inner { grid-template-columns: 1fr; text-align: center; }
  .hero-text h1 { font-size: 44px; }
  .hero-desc { margin-left: auto; margin-right: auto; }
  .hero-actions { justify-content: center; }
  .hero-visual { margin-top: 20px; }
  .features-grid { grid-template-columns: repeat(2, 1fr); }
  .screens-grid { grid-template-columns: repeat(3, 1fr); gap: 14px; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); gap: 30px; }
  .nav-links {
    position: fixed; top: 68px; left: 0; right: 0;
    background: #fff; flex-direction: column; gap: 0;
    max-height: 0; overflow: hidden; transition: max-height .3s;
    box-shadow: 0 10px 20px rgba(0,0,0,.06);
  }
  .nav-links a { padding: 16px 24px; border-top: 1px solid var(--border); }
  .nav-links.open { max-height: 400px; }
  .nav-toggle { display: flex; }
  .nav-download { display: none; }
}
@media (max-width: 560px) {
  .hero-text h1 { font-size: 36px; }
  .features-grid { grid-template-columns: 1fr; }
  .screens-grid { grid-template-columns: 1fr; }
  .phone-showcase { transform: scale(.8); }
  .section-head h2 { font-size: 28px; }
  .download-card h2 { font-size: 26px; }
}