/* ============ 基础 ============ */
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  color: #1a2233;
  background: #f6f8fb;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
a { text-decoration: none; color: inherit; }
.container { width: 100%; max-width: 1200px; margin: 0 auto; padding: 0 24px; }
.section-head { text-align: center; margin: 0 0 36px; }
.section-head h2 { font-size: 30px; font-weight: 700; letter-spacing: .5px; }
.section-head p { color: #6b7a90; margin-top: 8px; }
.section-head.light { color: #fff; }
.section-head.light p { color: rgba(255,255,255,.75); }

/* ============ 头部导航 ============ */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255,255,255,.9);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid #eceff4;
}
.header-inner { display: flex; align-items: center; justify-content: space-between; height: 68px; }
.brand { display: flex; align-items: center; }
.brand-logo { height: 34px; width: auto; display: block; }
@media (max-width: 620px) {
  .brand-logo { height: 28px; }
}
.nav { display: flex; gap: 26px; }
.nav a { font-size: 15px; color: #3a4761; transition: color .2s; }
.nav a:hover, .nav a.active { color: #4f6df5; }
.header-tools { display: flex; align-items: center; gap: 10px; }
.header-tools button {
  border: none; background: #eef1f7; width: 38px; height: 38px;
  border-radius: 10px; cursor: pointer; font-size: 16px;
}
.menu-btn { display: none; }
.mobile-menu {
  display: none; flex-direction: column; background: #fff;
  border-bottom: 1px solid #eceff4;
}
.mobile-menu.open { display: flex; }
.mobile-menu a { padding: 14px 24px; border-top: 1px solid #f2f4f9; color: #3a4761; }

/* ============ Hero ============ */
.hero {
  position: relative;
  background: linear-gradient(135deg, #23315c 0%, #3b4d86 45%, #5566a8 100%);
  color: #fff;
  padding: 90px 24px 120px;
  text-align: center;
  overflow: hidden;
}
.hero::after {
  content: ""; position: absolute; inset: 0;
  background: radial-gradient(circle at 20% 20%, rgba(122,79,240,.35), transparent 40%),
              radial-gradient(circle at 80% 70%, rgba(79,109,245,.4), transparent 45%);
  pointer-events: none;
}
.hero-inner { position: relative; z-index: 1; max-width: 760px; margin: 0 auto; }
.eyebrow { letter-spacing: 4px; font-size: 13px; color: #aeb8e0; }
.hero h1 { font-size: 46px; line-height: 1.25; font-weight: 800; margin: 18px 0; }
.hero-sub { font-size: 17px; color: #c8cfe9; margin-bottom: 34px; }
.hero-cta { display: flex; gap: 16px; justify-content: center; }
.btn { padding: 13px 28px; border-radius: 12px; font-size: 15px; font-weight: 600; transition: all .2s; }
.btn-solid { background: #4f6df5; color: #fff; box-shadow: 0 8px 20px rgba(79,109,245,.4); }
.btn-solid:hover { background: #3a59e8; transform: translateY(-2px); }
.btn-ghost { border: 1px solid rgba(255,255,255,.4); color: #fff; }
.btn-ghost:hover { background: rgba(255,255,255,.1); }
.hero-stats {
  position: relative; z-index: 1;
  display: flex; justify-content: center; gap: 48px; margin-top: 56px;
}
.stat strong { font-size: 30px; font-weight: 800; display: block; }
.stat span { font-size: 13px; color: #b6bfdf; }

/* ============ 瀑布流 ============ */
.masonry-section, .articles-section { padding: 70px 24px 20px; }
.masonry {
  column-count: 3;
  column-gap: 24px;
}
.card {
  position: relative;
  break-inside: avoid;
  margin: 0 0 24px;
  background: #fff;
  border-radius: 18px;
  overflow: hidden;
  box-shadow: 0 6px 24px rgba(30,50,90,.06);
  transition: transform .25s, box-shadow .25s;
}
.card:hover { transform: translateY(-6px); box-shadow: 0 14px 34px rgba(30,50,90,.14); }
.card-img {
  aspect-ratio: 16 / 10;
  display: flex; align-items: flex-end; padding: 16px;
  color: #fff; position: relative;
}
.article-card .card-img { aspect-ratio: 16 / 11; }
.article-card.is-tall .card-img { aspect-ratio: 3 / 4; }
.article-card.is-tall { min-height: 340px; }
.card-img-label {
  background: rgba(255,255,255,.22); backdrop-filter: blur(6px);
  padding: 5px 12px; border-radius: 20px; font-size: 12px; font-weight: 600;
}
.card-body { padding: 20px 22px 24px; }
.card-body h3 { font-size: 18px; font-weight: 700; margin-bottom: 8px; color: #1a2233; }
.card-body p { font-size: 14px; color: #6b7a90; }
.card-meta { margin-top: 14px; font-size: 12px; color: #9aa7bd; }

/* ============ 应用领域 ============ */
.apps-section { padding: 70px 24px; }
.apps-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.app-card {
  background: #fff; border-radius: 16px; padding: 26px 20px;
  text-align: center; box-shadow: 0 6px 24px rgba(30,50,90,.06);
  transition: transform .2s;
}
.app-card:hover { transform: translateY(-4px); }
.app-card span { font-size: 28px; }
.app-card strong { display: block; margin-top: 10px; font-size: 16px; }

/* ============ 关于 · 联系 ============ */
.about-band { background: #1d2740; color: #fff; padding: 70px 0; }
.about-text { max-width: 820px; margin: 0 auto; text-align: center; color: #c0c9e0; font-size: 16px; }
.contact-band { padding: 70px 24px; }
.contact-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.contact-item { background: #fff; border-radius: 16px; padding: 26px; box-shadow: 0 6px 24px rgba(30,50,90,.06); }
.contact-item span { font-size: 24px; }
.contact-item strong { display: block; margin-top: 8px; }
.contact-item p { color: #6b7a90; font-size: 14px; margin-top: 4px; }

/* ============ 页脚 ============ */
.site-footer { background: #161d33; color: #8b93ad; padding: 28px 0; text-align: center; font-size: 13px; }

/* ============ 响应式 ============ */
@media (max-width: 900px) {
  .masonry { column-count: 2; }
  .hero h1 { font-size: 34px; }
  .hero-stats { gap: 28px; }
  .apps-grid, .contact-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 620px) {
  .nav { display: none; }
  .menu-btn { display: block; }
  .masonry { column-count: 1; }
  .hero h1 { font-size: 28px; }
  .hero-cta { flex-direction: column; }
  .hero-stats { flex-direction: column; gap: 18px; }
  .apps-grid, .contact-grid { grid-template-columns: 1fr; }
}