/* ===== 设计变量 ===== */
:root {
  --brand: #1d4ed8;
  --brand-dark: #1e3a8a;
  --accent: #06b6d4;
  --ink: #0f172a;
  --muted: #64748b;
  --line: #e2e8f0;
  --bg: #ffffff;
  --bg-alt: #f8fafc;
  --radius: 14px;
  --shadow: 0 10px 30px rgba(15, 23, 42, 0.08);
  --maxw: 1120px;
}

/* ===== 基础重置 ===== */
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", Roboto, Helvetica, Arial, sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
h1, h2, h3 { line-height: 1.25; margin: 0 0 .5em; }
p { margin: 0 0 1em; }
.container { width: 100%; max-width: var(--maxw); margin: 0 auto; padding: 0 20px; }
.muted { color: var(--muted); }

/* ===== 按钮 ===== */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 12px 22px; border-radius: 999px; font-weight: 600;
  border: 1px solid transparent; cursor: pointer; transition: .2s;
  font-size: 15px;
}
.btn-sm { padding: 8px 16px; font-size: 14px; }
.btn-primary { background: var(--brand); color: #fff; }
.btn-primary:hover { background: var(--brand-dark); }
.btn-ghost { background: transparent; border-color: var(--line); color: var(--ink); }
.btn-ghost:hover { border-color: var(--brand); color: var(--brand); }

/* ===== 顶部导航 ===== */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255,255,255,.85); backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}
.nav { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.brand { display: flex; align-items: center; gap: 8px; font-weight: 800; font-size: 18px; color: var(--brand-dark); }
.brand img { border-radius: 8px; }
.nav-menu { display: flex; align-items: center; gap: 22px; }
.nav-menu a { color: var(--ink); font-weight: 500; }
.nav-menu a:hover { color: var(--brand); }
.nav-toggle { display: none; flex-direction: column; gap: 5px; background: none; border: 0; cursor: pointer; padding: 8px; }
.nav-toggle span { width: 24px; height: 2px; background: var(--ink); transition: .2s; }

/* ===== Hero ===== */
.hero { padding: 72px 0 56px; background: linear-gradient(180deg, #eef4ff 0%, #ffffff 70%); }
.hero-grid { display: grid; grid-template-columns: 1.1fr .9fr; gap: 40px; align-items: center; }
.badge { display: inline-block; padding: 6px 14px; border-radius: 999px; background: #e0ecff; color: var(--brand); font-weight: 600; font-size: 13px; margin-bottom: 16px; }
.hero h1 { font-size: clamp(32px, 5vw, 52px); font-weight: 800; letter-spacing: -.5px; }
.lead { font-size: 18px; color: var(--muted); max-width: 540px; }
.hero-actions { display: flex; gap: 14px; margin: 24px 0 28px; flex-wrap: wrap; }
.hero-stats { display: flex; gap: 28px; list-style: none; padding: 0; margin: 0; flex-wrap: wrap; }
.hero-stats li { display: flex; flex-direction: column; }
.hero-stats strong { font-size: 22px; color: var(--brand); }
.hero-stats span { font-size: 13px; color: var(--muted); }

/* Hero 视觉：漂浮工具标签 */
.hero-visual { position: relative; min-height: 320px; }
.chip {
  position: absolute; padding: 12px 18px; border-radius: 14px; background: #fff;
  box-shadow: var(--shadow); font-weight: 600; color: var(--brand-dark);
  border: 1px solid var(--line);
}
.chip-1 { top: 10%; left: 8%; }
.chip-2 { top: 4%; right: 6%; color: var(--accent); }
.chip-3 { top: 46%; left: 0; }
.chip-4 { bottom: 14%; right: 4%; color: var(--accent); }
.chip-5 { bottom: 2%; left: 22%; }

/* ===== 通用区块 ===== */
.section { padding: 72px 0; }
.section-alt { background: var(--bg-alt); }
.section-head { text-align: center; max-width: 640px; margin: 0 auto 40px; }
.section-head.left { text-align: left; margin-left: 0; }
.section-head h2 { font-size: clamp(26px, 3.5vw, 36px); }
.section-head p { color: var(--muted); font-size: 17px; }

/* ===== 工具卡片 ===== */
.cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.card {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius);
  padding: 26px; transition: .2s; box-shadow: 0 1px 2px rgba(15,23,42,.04);
}
.card:hover { transform: translateY(-4px); box-shadow: var(--shadow); border-color: #c7d7ff; }
.card-icon {
  width: 52px; height: 52px; border-radius: 12px; display: grid; place-items: center;
  background: #eef4ff; color: var(--brand); margin-bottom: 16px;
}
.card h3 { font-size: 19px; }
.card p { color: var(--muted); margin: 0; }

/* ===== 核心优势 ===== */
.features { display: grid; grid-template-columns: repeat(4, 1fr); gap: 22px; }
.feature { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 24px; }
.feature h3 { font-size: 18px; color: var(--brand); }
.feature p { color: var(--muted); margin: 0; }

/* ===== 关于 ===== */
.about-grid { display: grid; grid-template-columns: 1.4fr .8fr; gap: 40px; align-items: start; }
.about-card { background: linear-gradient(160deg, var(--brand), var(--brand-dark)); color: #fff; border-radius: var(--radius); padding: 28px; }
.about-card h3 { color: #fff; font-size: 22px; }
.about-card ul { list-style: none; padding: 0; margin: 0; }
.about-card li { padding: 10px 0; border-top: 1px solid rgba(255,255,255,.18); }
.about-card li:first-of-type { border-top: 0; }
.about-card span { display: block; font-size: 12px; opacity: .8; }

/* ===== 联系 ===== */
.contact-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; align-items: start; }
.contact-list { list-style: none; padding: 0; margin: 12px 0 0; }
.contact-list li { padding: 12px 0; border-bottom: 1px solid var(--line); }
.contact-list strong { display: inline-block; width: 56px; color: var(--muted); font-weight: 600; }
.contact-form { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 26px; box-shadow: var(--shadow); }
.field { margin-bottom: 16px; }
.field label { display: block; font-weight: 600; margin-bottom: 6px; font-size: 14px; }
.field input, .field textarea {
  width: 100%; padding: 12px 14px; border: 1px solid var(--line); border-radius: 10px;
  font: inherit; color: var(--ink); background: #fff; transition: .15s;
}
.field input:focus, .field textarea:focus { outline: none; border-color: var(--brand); box-shadow: 0 0 0 3px rgba(29,78,216,.15); }
.form-note { margin: 10px 0 0; font-size: 14px; color: var(--brand); min-height: 20px; }

/* ===== 页脚 ===== */
.site-footer { background: #0f172a; color: #cbd5e1; padding: 48px 0 24px; }
.brand-light { color: #fff; }
.footer-grid { display: flex; justify-content: space-between; gap: 24px; flex-wrap: wrap; }
.footer-links { display: flex; gap: 22px; flex-wrap: wrap; }
.footer-links a { color: #cbd5e1; }
.footer-links a:hover { color: #fff; }
.footer-bottom { border-top: 1px solid rgba(255,255,255,.12); margin-top: 28px; padding-top: 18px; font-size: 13px; color: #94a3b8; }

/* ===== 响应式 ===== */
@media (max-width: 900px) {
  .hero-grid, .about-grid, .contact-grid { grid-template-columns: 1fr; }
  .cards { grid-template-columns: repeat(2, 1fr); }
  .features { grid-template-columns: repeat(2, 1fr); }
  .hero-visual { min-height: 240px; }
}
@media (max-width: 640px) {
  .nav-menu {
    position: absolute; top: 64px; left: 0; right: 0; background: #fff;
    flex-direction: column; align-items: stretch; gap: 0; padding: 8px 20px 16px;
    border-bottom: 1px solid var(--line); display: none;
  }
  .nav-menu.open { display: flex; }
  .nav-menu a { padding: 12px 0; }
  .nav-toggle { display: flex; }
  .cards, .features { grid-template-columns: 1fr; }
  .hero-stats { gap: 18px; }
}