/* ============================================
   css/style.css - 全局样式表
   上海天瀚星御科技有限公司
   ============================================ */

/* ----- 导入字体 ----- */
@import url('https://fonts.googleapis.com/css2?family=Inter:opsz,wght@14..32,400;14..32,500;14..32,600;14..32,700&display=swap');

/* ----- CSS 变量（主题色） ----- */
:root {
  --primary: #0057b3;
  --primary-dark: #003d7a;
  --primary-light: #e8f0fe;
  --secondary: #0b1a2e;
  --accent: #00a3b2;
  --gray-50: #f8fafc;
  --gray-100: #f1f4f8;
  --gray-200: #e2e8f0;
  --gray-300: #cbd5e1;
  --gray-400: #94a3b8;
  --gray-500: #64748b;
  --gray-600: #475569;
  --gray-700: #334155;
  --gray-800: #1e293b;
  --gray-900: #0f172a;
  --white: #ffffff;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 16px rgba(0,20,40,0.08);
  --shadow-lg: 0 12px 48px rgba(0,20,40,0.12);
  --radius: 12px;
  --radius-sm: 6px;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ----- 全局重置 ----- */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background-color: var(--gray-50);
  color: var(--gray-800);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a {
  text-decoration: none;
  color: inherit;
  transition: var(--transition);
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

ul {
  list-style: none;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 80px 0;
}

.section-title {
  font-size: 2.2rem;
  font-weight: 700;
  color: var(--gray-900);
  text-align: center;
  margin-bottom: 16px;
  letter-spacing: -0.5px;
}

.section-subtitle {
  text-align: center;
  font-size: 1.1rem;
  color: var(--gray-500);
  max-width: 640px;
  margin: 0 auto 48px;
}

/* ----- 按钮 ----- */
.btn {
  display: inline-block;
  padding: 12px 32px;
  border-radius: 50px;
  font-weight: 600;
  font-size: 0.95rem;
  border: none;
  cursor: pointer;
  transition: var(--transition);
  text-align: center;
}

.btn-primary {
  background: var(--primary);
  color: var(--white);
  box-shadow: 0 4px 14px rgba(0, 87, 179, 0.3);
}
.btn-primary:hover {
  background: var(--primary-dark);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0, 87, 179, 0.35);
}

.btn-outline {
  background: transparent;
  color: var(--primary);
  border: 2px solid var(--primary);
}
.btn-outline:hover {
  background: var(--primary);
  color: var(--white);
  transform: translateY(-2px);
}

.btn-white {
  background: var(--white);
  color: var(--primary);
}
.btn-white:hover {
  background: var(--gray-100);
  transform: translateY(-2px);
}

/* ----- 顶部备案号栏 ----- */
.top-bar {
  background: var(--secondary);
  color: rgba(255,255,255,0.75);
  font-size: 0.8rem;
  padding: 8px 0;
  text-align: center;
  border-bottom: 1px solid #1e3448;
}

.top-bar a {
  color: #7db9ff;
  font-weight: 500;
}
.top-bar a:hover {
  color: #b3d6ff;
  text-decoration: underline;
}

/* ----- 导航栏 ----- */
.navbar {
  background: var(--white);
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 0;
  z-index: 1000;
  padding: 14px 0;
  border-bottom: 1px solid var(--gray-200);
}

.navbar .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 1.3rem;
  color: var(--gray-900);
}

.logo i {
  color: var(--primary);
  font-size: 1.8rem;
}

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

.logo .tagline {
  font-size: 0.7rem;
  font-weight: 400;
  color: var(--gray-500);
  margin-left: 12px;
  padding-left: 12px;
  border-left: 2px solid var(--gray-200);
  display: none;
}

@media (min-width: 768px) {
  .logo .tagline { display: inline; }
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
  font-weight: 500;
  font-size: 0.95rem;
}

.nav-links a {
  color: var(--gray-600);
  position: relative;
}
.nav-links a:hover {
  color: var(--primary);
}
.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--primary);
  transition: var(--transition);
}
.nav-links a:hover::after {
  width: 100%;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

.nav-actions .btn {
  padding: 8px 20px;
  font-size: 0.85rem;
}

/* 移动端汉堡菜单 */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  background: none;
  border: none;
  padding: 4px;
}
.hamburger span {
  display: block;
  width: 28px;
  height: 3px;
  background: var(--gray-700);
  border-radius: 3px;
  transition: var(--transition);
}

@media (max-width: 992px) {
  .nav-links {
    display: none;
    flex-direction: column;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--white);
    padding: 24px;
    gap: 16px;
    box-shadow: var(--shadow-lg);
    border-top: 1px solid var(--gray-200);
  }
  .nav-links.open {
    display: flex;
  }
  .hamburger {
    display: flex;
  }
  .nav-actions .btn {
    display: none;
  }
}

/* ----- 通用卡片 ----- */
.card {
  background: var(--white);
  border-radius: var(--radius);
  padding: 32px;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
  border: 1px solid var(--gray-200);
}
.card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-4px);
}

.card-icon {
  font-size: 2.5rem;
  color: var(--primary);
  margin-bottom: 16px;
}

.card h3 {
  font-size: 1.2rem;
  margin-bottom: 10px;
  color: var(--gray-900);
}

.card p {
  color: var(--gray-500);
  font-size: 0.95rem;
}

/* ----- 页脚 ----- */
.footer {
  background: var(--secondary);
  color: rgba(255,255,255,0.7);
  padding: 60px 0 24px;
}

.footer .container {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
}

.footer-brand h3 {
  color: var(--white);
  font-size: 1.3rem;
  margin-bottom: 12px;
}
.footer-brand h3 i {
  color: var(--primary);
  margin-right: 8px;
}
.footer-brand p {
  font-size: 0.9rem;
  max-width: 300px;
}

.footer-links h4 {
  color: var(--white);
  margin-bottom: 16px;
  font-size: 1rem;
}
.footer-links a {
  display: block;
  padding: 4px 0;
  font-size: 0.9rem;
}
.footer-links a:hover {
  color: var(--white);
}

.footer-bottom {
  grid-column: 1 / -1;
  border-top: 1px solid rgba(255,255,255,0.08);
  padding-top: 24px;
  margin-top: 16px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  font-size: 0.85rem;
}
.footer-bottom a {
  color: #7db9ff;
}
.footer-bottom a:hover {
  color: #b3d6ff;
}

@media (max-width: 768px) {
  .footer .container {
    grid-template-columns: 1fr 1fr;
    gap: 32px;
  }
  .footer-bottom {
    flex-direction: column;
    text-align: center;
  }
}

@media (max-width: 480px) {
  .footer .container {
    grid-template-columns: 1fr;
  }
}

/* ----- 工具类 ----- */
.text-center { text-align: center; }
.mt-16 { margin-top: 16px; }
.mt-32 { margin-top: 32px; }
.mb-16 { margin-bottom: 16px; }
.mb-32 { margin-bottom: 32px; }
.gap-16 { gap: 16px; }
.gap-24 { gap: 24px; }
.flex-center { display: flex; align-items: center; justify-content: center; }
.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 32px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 32px; }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }

@media (max-width: 768px) {
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; gap: 24px; }
}
@media (min-width: 769px) and (max-width: 1024px) {
  .grid-3 { grid-template-columns: 1fr 1fr; }
  .grid-4 { grid-template-columns: 1fr 1fr; }
}