/* ============================================
   理工创客少年AI学院 - 全局样式
   设计风格：平面极简，高级感
============================================ */

:root {
  --primary: #1a1a2e;
  --accent: #0f9d58;
  --accent-light: #34c47a;
  --accent-soft: #e8f8f0;
  --blue: #1565c0;
  --blue-light: #e3f0ff;
  --text-main: #1a1a2e;
  --text-sub: #6b7280;
  --text-light: #9ca3af;
  --bg: #f7f8fa;
  --bg-white: #ffffff;
  --border: #e5e7eb;
  --shadow: 0 2px 12px rgba(0,0,0,0.07);
  --shadow-hover: 0 8px 30px rgba(0,0,0,0.12);
  --radius: 12px;
  --radius-sm: 8px;
  --transition: all 0.25s ease;
}

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

body {
  font-family: -apple-system, 'PingFang SC', 'Microsoft YaHei', 'Segoe UI', sans-serif;
  background: var(--bg);
  color: var(--text-main);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a { text-decoration: none; color: inherit; }
img { display: block; max-width: 100%; }
ul, ol { list-style: none; }

/* ---- 按钮 ---- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 10px 22px;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  white-space: nowrap;
}
.btn-primary {
  background: var(--accent);
  color: #fff;
}
.btn-primary:hover { background: var(--accent-light); transform: translateY(-1px); box-shadow: 0 4px 16px rgba(15,157,88,0.3); }
.btn-outline {
  background: transparent;
  color: var(--accent);
  border: 1.5px solid var(--accent);
}
.btn-outline:hover { background: var(--accent-soft); }
.btn-dark {
  background: var(--primary);
  color: #fff;
}
.btn-dark:hover { opacity: 0.85; }
.btn-lg { padding: 14px 32px; font-size: 16px; border-radius: 10px; }
.btn-sm { padding: 7px 16px; font-size: 13px; }

/* ---- 导航 ---- */
.navbar {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: rgba(255,255,255,0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
  height: 64px;
  display: flex;
  align-items: center;
}
.nav-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 17px;
  font-weight: 700;
  color: var(--primary);
}
.nav-logo .logo-icon {
  width: 34px;
  height: 34px;
  background: var(--primary);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent);
  font-weight: 900;
  font-size: 16px;
}
.nav-menu {
  display: flex;
  align-items: center;
  gap: 4px;
}
.nav-menu a {
  padding: 6px 16px;
  border-radius: 8px;
  font-size: 15px;
  font-weight: 500;
  color: var(--text-sub);
  transition: var(--transition);
}
.nav-menu a:hover, .nav-menu a.active {
  color: var(--accent);
  background: var(--accent-soft);
}
.nav-actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

/* ---- 容器 ---- */
.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; }
.section { padding: 72px 0; }
.section-sm { padding: 48px 0; }
.section-title {
  font-size: 28px;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 8px;
}
.section-sub {
  font-size: 15px;
  color: var(--text-sub);
  margin-bottom: 40px;
}

/* ---- 卡片 ---- */
.card {
  background: var(--bg-white);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  overflow: hidden;
  transition: var(--transition);
}
.card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-hover);
}

/* ---- 标签 ---- */
.tag {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 4px;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.3px;
}
.tag-green { background: var(--accent-soft); color: var(--accent); }
.tag-blue { background: var(--blue-light); color: var(--blue); }
.tag-dark { background: #f0f0f5; color: var(--text-sub); }

/* ---- 徽章 ---- */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 2px 8px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 600;
}
.badge-green { background: #d1fae5; color: #065f46; }
.badge-gray { background: #f3f4f6; color: #6b7280; }

/* ---- Footer ---- */
footer {
  background: var(--primary);
  color: rgba(255,255,255,0.7);
  padding: 40px 0 24px;
}
.footer-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  padding-bottom: 32px;
  border-bottom: 1px solid rgba(255,255,255,0.1);
  margin-bottom: 24px;
}
.footer-brand { font-size: 17px; font-weight: 700; color: #fff; margin-bottom: 10px; }
.footer-desc { font-size: 13px; line-height: 1.8; }
.footer-col h4 { color: #fff; font-size: 14px; font-weight: 600; margin-bottom: 14px; }
.footer-col ul li { margin-bottom: 8px; }
.footer-col ul li a { font-size: 13px; color: rgba(255,255,255,0.6); transition: var(--transition); }
.footer-col ul li a:hover { color: var(--accent-light); }
.footer-copy { font-size: 13px; text-align: center; }

/* ---- 响应式 ---- */
@media (max-width: 768px) {
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 24px; }
  .section { padding: 48px 0; }
  .section-title { font-size: 22px; }
}
@media (max-width: 480px) {
  .footer-grid { grid-template-columns: 1fr; }
}