:root {
  --primary: #6ea8fe;
  --primary-dark: #4d8df0;
  --bg: #0d0f14;
  --bg-soft: #14181f;
  --bg-card: #161b23;
  --border: #262d38;
  --text: #e8eaee;
  --text-light: #9aa2ae;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: "Helvetica Neue", "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
  color: var(--text);
  line-height: 1.7;
  background: var(--bg);
}

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(13, 15, 20, 0.85);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.logo {
  font-size: 26px;
  font-weight: 700;
  color: var(--text);
  text-decoration: none;
  letter-spacing: 1px;
}

.logo span {
  color: var(--primary);
}

.nav a {
  color: var(--text-light);
  text-decoration: none;
  margin-left: 28px;
  font-size: 15px;
  transition: color 0.2s;
}

.nav a:hover {
  color: var(--primary);
}

/* Hero */
.hero {
  background: linear-gradient(135deg, #10141c, #0a0c11);
  color: var(--text);
  text-align: center;
  padding: 120px 20px 130px;
  border-bottom: 1px solid var(--border);
}

.hero h1 {
  font-size: 56px;
  letter-spacing: 6px;
  background: linear-gradient(120deg, #fff, var(--primary));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-tagline {
  font-size: 18px;
  margin: 20px 0 36px;
  color: var(--text-light);
}

.btn {
  display: inline-block;
  background: var(--primary);
  color: #0d0f14;
  padding: 12px 36px;
  border-radius: 4px;
  text-decoration: none;
  font-weight: 600;
  transition: transform 0.2s, box-shadow 0.2s;
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 18px rgba(110, 168, 254, 0.3);
}

/* Sections */
.section {
  padding: 80px 0;
}

.section-alt {
  background: var(--bg-soft);
}

.section-title {
  font-size: 30px;
  text-align: center;
  color: var(--text);
  margin-bottom: 12px;
}

.section-title::after {
  content: "";
  display: block;
  width: 48px;
  height: 3px;
  background: var(--primary);
  margin: 12px auto 24px;
}

.section-desc {
  max-width: 720px;
  margin: 0 auto;
  text-align: center;
  color: var(--text-light);
}

/* Cards */
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 24px;
  margin-top: 40px;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 32px 24px;
  text-align: center;
  transition: transform 0.2s, box-shadow 0.2s, border-color 0.2s;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.4);
  border-color: var(--primary);
}

.card h3 {
  color: var(--primary);
  margin-bottom: 10px;
  font-size: 20px;
}

.card p {
  color: var(--text-light);
  font-size: 14px;
}

/* Contact */
.contact {
  max-width: 560px;
  margin: 30px auto 0;
}

.contact-item {
  display: flex;
  justify-content: space-between;
  padding: 16px 0;
  border-bottom: 1px solid var(--border);
}

.contact-item .label {
  color: var(--primary);
  font-weight: 600;
}

/* Footer */
.site-footer {
  background: #08090c;
  color: var(--text-light);
  border-top: 1px solid var(--border);
  text-align: center;
  padding: 26px 0;
  font-size: 14px;
}

@media (max-width: 640px) {
  .hero h1 {
    font-size: 38px;
  }
  .nav a {
    margin-left: 16px;
  }
}