:root {
  --blue-900: #0a2a6b;
  --blue-700: #1545c9;
  --blue-600: #1d5ff0;
  --blue-500: #287dfa;
  --blue-300: #6ea4ff;
  --blue-50: #eef4ff;
  --ink: #1a202c;
  --gray: #718096;
  --line: #e2e8f0;
  --bg: #ffffff;
  --maxw: 1120px;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", Roboto, Helvetica, Arial, sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.6;
}
a { color: var(--blue-600); text-decoration: none; }
a:hover { color: var(--blue-700); }
h1, h2, h3 { color: var(--blue-900); line-height: 1.25; margin: 0 0 .5em; }
h1 { font-size: clamp(2rem, 5vw, 3.2rem); }
h2 { font-size: clamp(1.6rem, 3.5vw, 2.4rem); }
h3 { font-size: 1.25rem; }
p { margin: 0 0 1em; }

.container { width: 100%; max-width: var(--maxw); margin: 0 auto; padding: 0 20px; }
.section { padding: 72px 0; }
.section--alt { background: var(--blue-50); }

/* header */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255,255,255,.92);
  border-bottom: 1px solid var(--line);
  backdrop-filter: saturate(180%) blur(8px);
}
.site-header .container {
  display: flex; align-items: center; justify-content: space-between; height: 64px;
}
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; color: var(--blue-900); font-size: 1.15rem; }
.brand svg { width: 36px; height: 24px; transition: transform .5s ease; }
.brand:hover svg { transform: rotate(180deg); }
.nav { display: flex; align-items: center; gap: 24px; }
.nav a { color: var(--ink); font-weight: 500; }
.nav a.active { color: var(--blue-600); }
.nav a:hover { color: var(--blue-600); }
.lang-switch {
  border: 1px solid var(--line); border-radius: 999px; padding: 4px 12px;
  font-size: .85rem; color: var(--blue-700);
}
.nav-toggle { display: none; background: none; border: 0; cursor: pointer; font-size: 1.5rem; }

/* buttons */
.btn {
  display: inline-block; padding: 12px 24px; border-radius: 8px; font-weight: 600;
  cursor: pointer; border: 1px solid transparent; transition: all .15s ease;
}
.btn-primary { background: var(--blue-600); color: #fff; }
.btn-primary:hover { background: var(--blue-700); color: #fff; }
.btn-outline { background: #fff; color: var(--blue-600); border-color: var(--blue-300); }
.btn-outline:hover { background: var(--blue-50); }

/* cards */
.grid { display: grid; gap: 24px; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.card {
  background: #fff; border: 1px solid var(--line); border-radius: 12px;
  padding: 28px; transition: box-shadow .15s ease, transform .15s ease;
}
.card:hover { box-shadow: 0 8px 24px rgba(13,71,161,.08); transform: translateY(-2px); }
.card h3 { color: var(--blue-700); }

/* hero */
.hero { background: linear-gradient(135deg, var(--blue-50), #fff); padding: 96px 0; text-align: center; }
.hero .lead { font-size: 1.2rem; color: var(--gray); max-width: 640px; margin: 0 auto 28px; }
.hero-actions { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; }

/* stats */
.stats { display: flex; gap: 32px; justify-content: center; flex-wrap: wrap; text-align: center; }
.stat .num { font-size: 2.4rem; font-weight: 800; color: var(--blue-600); }
.stat .label { color: var(--gray); }

/* form */
.form { max-width: 560px; }
.form .field { margin-bottom: 16px; }
.form label { display: block; margin-bottom: 6px; font-weight: 500; font-size: .9rem; }
.form input, .form textarea {
  width: 100%; padding: 12px 14px; border: 1px solid var(--line); border-radius: 8px;
  font: inherit; color: var(--ink); background: #fff;
}
.form input:focus, .form textarea:focus { outline: none; border-color: var(--blue-500); box-shadow: 0 0 0 3px var(--blue-50); }
.form textarea { min-height: 140px; resize: vertical; }
.form .err { border-color: #e53e3e; }

/* flash */
.flash { padding: 12px 16px; border-radius: 8px; margin-bottom: 16px; }
.flash.success { background: #e6fffa; color: #234e52; border: 1px solid #b2f5ea; }
.flash.error { background: #fff5f5; color: #742a2a; border: 1px solid #fed7d7; }

.contact-info { display: grid; gap: 12px; }
.contact-info div span { color: var(--gray); display: block; font-size: .85rem; }

/* footer */
.site-footer { background: var(--blue-900); color: #cdd9ff; padding: 40px 0; margin-top: 0; }
.site-footer a { color: #cdd9ff; }
.site-footer .container { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 12px; }
.footer-brand { display: flex; align-items: center; gap: 10px; font-weight: 700; color: #fff; }
.footer-brand svg { width: 36px; height: 24px; }

/* responsive */
@media (max-width: 820px) {
  .grid-2, .grid-3 { grid-template-columns: 1fr; }
  .nav {
    position: fixed; inset: 64px 0 auto 0; background: #fff; flex-direction: column;
    align-items: stretch; gap: 0; padding: 8px 20px; border-bottom: 1px solid var(--line);
    display: none;
  }
  .nav.open { display: flex; }
  .nav a { padding: 12px 0; border-bottom: 1px solid var(--line); }
  .nav-toggle { display: block; }
  .site-header .container { position: relative; }
  .lang-switch { position: absolute; right: 52px; top: 50%; transform: translateY(-50%); }
}