/* ============================================
   移动安全教材网站 - 全局样式
   主色调: 深蓝 #1e3a5f, 青蓝 #2c5282, 墨绿 #234e52
   辅助色: 浅灰 #f7fafc, 白色 #ffffff
   ============================================ */

/* CSS Variables */
:root {
    --primary-dark: #1e3a5f;
    --primary: #2c5282;
    --primary-light: #3182ce;
    --accent: #234e52;
    --accent-light: #2d6a6e;
    --text-primary: #1a202c;
    --text-secondary: #4a5568;
    --text-muted: #718096;
    --bg-primary: #ffffff;
    --bg-secondary: #f7fafc;
    --bg-tertiary: #edf2f7;
    --border: #e2e8f0;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.15);
    --radius-sm: 4px;
    --radius: 8px;
    --radius-lg: 12px;
    --transition: all 0.3s ease;
}

/* Reset & Base */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family:
        -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
        "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Helvetica,
        Arial, sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
}

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

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

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

/* Typography */
h1,
h2,
h3,
h4,
h5,
h6 {
    font-weight: 600;
    line-height: 1.3;
    color: var(--text-primary);
}

h1 {
    font-size: 2.5rem;
}
h2 {
    font-size: 2rem;
}
h3 {
    font-size: 1.5rem;
}
h4 {
    font-size: 1.25rem;
}

p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

/* Container */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

.container-narrow {
    max-width: 900px;
}

/* Section */
.section {
    padding: 3.5rem 0;
}

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

.section-header {
    text-align: center;
    margin-bottom: 2.5rem;
}

.section-title {
    font-size: 1.875rem;
    color: var(--primary-dark);
    margin-bottom: 0.625rem;
}

.section-subtitle {
    font-size: 1.05rem;
    color: var(--text-muted);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.75rem;
    font-size: 0.95rem;
    font-weight: 500;
    border-radius: var(--radius);
    cursor: pointer;
    transition: var(--transition);
    border: none;
    gap: 0.5rem;
    min-height: 44px;
}

.btn-primary {
    background-color: var(--primary-dark);
    color: white;
    border: none;
}

.btn-primary:hover {
    background-color: var(--primary);
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(30, 58, 95, 0.25);
}

.btn-secondary {
    background-color: transparent;
    color: var(--primary);
    border: 2px solid var(--primary);
}

.btn-secondary:hover {
    background-color: var(--primary);
    color: white;
}

.btn-outline {
    background-color: transparent;
    color: white;
    border: 2px solid rgba(255, 255, 255, 0.5);
}

.btn-outline:hover {
    background-color: rgba(255, 255, 255, 0.1);
    border-color: white;
}

.btn-sm {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

/* Cards */
.card {
    background: white;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    overflow: hidden;
    transition: var(--transition);
}

.card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}

.card-body {
    padding: 1.5rem;
}

/* Grid */
.grid {
    display: grid;
    gap: 2rem;
}

.grid-3 {
    grid-template-columns: repeat(3, 1fr);
}

.grid-2 {
    grid-template-columns: repeat(2, 1fr);
}

/* Badge */
.badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    font-size: 0.75rem;
    font-weight: 500;
    border-radius: 9999px;
    background-color: var(--bg-tertiary);
    color: var(--text-secondary);
}

.badge-primary {
    background-color: var(--primary);
    color: white;
}

/* Header */
.header {
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
}

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

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-weight: 600;
    font-size: 1.125rem;
    color: var(--primary-dark);
}

.logo-img {
    height: 36px;
    width: auto;
    display: block;
}

.nav {
    display: flex;
    gap: 2rem;
}

.nav a {
    color: var(--text-secondary);
    font-weight: 500;
    padding: 0.5rem 0;
    position: relative;
}

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

.nav a.active::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 2px;
    background-color: var(--primary);
}

/* Footer */
.footer {
    background-color: var(--primary-dark);
    color: rgba(255, 255, 255, 0.8);
    padding: 3rem 0 1.5rem;
}

.footer-grid {
    display: grid;
    grid-template-columns: 1fr 1.5fr;
    gap: 6rem;
    margin-bottom: 2rem;
}

.footer-brand {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1rem;
    color: white;
    font-weight: 600;
}

.footer-logo-img {
    height: 40px;
    width: auto;
    display: block;
}

.footer-desc {
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.9rem;
    line-height: 1.6;
}

.footer-title {
    color: white;
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: 0.5rem;
}

.footer-links a {
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.9rem;
}

.footer-links a:hover {
    color: white;
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 1.5rem;
    text-align: center;
    font-size: 0.875rem;
}

.footer-bottom p {
    color: rgba(255, 255, 255, 0.7);
    margin-bottom: 0;
}

/* Responsive */
@media (max-width: 992px) {
    .grid-3 {
        grid-template-columns: repeat(2, 1fr);
    }

    .footer-grid {
        grid-template-columns: 1fr 1.2fr;
        gap: 4rem;
    }
}

@media (max-width: 768px) {
    h1 {
        font-size: 2rem;
    }
    h2 {
        font-size: 1.75rem;
    }
    h3 {
        font-size: 1.25rem;
    }

    .section {
        padding: 3rem 0;
    }

    .grid-3,
    .grid-2 {
        grid-template-columns: 1fr;
    }

    .nav {
        display: none;
    }

    .footer-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
}

/* Utility Classes */
.text-center {
    text-align: center;
}
.text-primary {
    color: var(--primary);
}
.text-muted {
    color: var(--text-muted);
}
.mt-1 {
    margin-top: 0.5rem;
}
.mt-2 {
    margin-top: 1rem;
}
.mt-3 {
    margin-top: 1.5rem;
}
.mt-4 {
    margin-top: 2rem;
}
.mb-1 {
    margin-bottom: 0.5rem;
}
.mb-2 {
    margin-bottom: 1rem;
}
.mb-3 {
    margin-bottom: 1.5rem;
}
.mb-4 {
    margin-bottom: 2rem;
}