/**
 * China Travel Guide - Modern UI Styles
 * 中国旅行攻略网站 - 现代 UI 样式
 * 
 * 设计风格：现代、简洁、高级、大图背景
 * 灵感来源：https://www.argentina.travel
 */

/* ============================================================
   CSS Variables - Modern Color Palette
   ============================================================ */
:root {
    /* Primary Colors */
    --primary-dark: #1a3a52;        /* 深蓝 - 主色深色 */
    --primary: #2c5f8d;             /* 蓝色 - 主色 */
    --primary-light: #5bc0de;       /* 浅蓝 - 主色浅色 */
    --accent: #98ddca;              /* 青绿 - 强调色 */
    
    /* Text Colors */
    --text-dark: #1a1a2e;           /* 深色文字 */
    --text-medium: #4a5568;         /* 中等文字 */
    --text-light: #718096;          /* 浅色文字 */
    --text-white: #ffffff;          /* 白色文字 */
    
    /* Background Colors */
    --bg-white: #ffffff;            /* 白色背景 */
    --bg-light: #f7fafc;            /* 浅灰背景 */
    --bg-gradient: linear-gradient(135deg, #f7fafc 0%, #ffffff 100%);
    
    /* UI Elements */
    --border-color: #e2e8f0;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.06);
    --shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.15);
    --shadow-hover: 0 15px 50px rgba(0, 0, 0, 0.12);
    
    /* Transitions */
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ============================================================
   Base Styles - Modern Reset
   ============================================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    font-size: 17px;
    line-height: 1.8;
    color: var(--text-dark);
    background: var(--bg-gradient);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}

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

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

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

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 30px;
}

/* ============================================================
   Navigation - Modern Transparent
   ============================================================ */
.navbar {
    background: rgba(255, 255, 255, 0.95) !important;
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
    padding: 20px 0;
    transition: var(--transition);
}

.navbar.scrolled {
    padding: 15px 0;
    box-shadow: var(--shadow);
}

.navbar-brand {
    font-size: 22px;
    font-weight: 800;
    color: var(--primary-dark) !important;
    letter-spacing: -0.5px;
}

.nav-link {
    font-weight: 600;
    color: var(--text-medium) !important;
    padding: 10px 20px !important;
    transition: var(--transition);
}

.nav-link:hover {
    color: var(--primary) !important;
}

.dropdown-menu {
    border: none;
    box-shadow: var(--shadow-lg);
    border-radius: 16px;
    padding: 12px;
    margin-top: 10px;
}

.dropdown-item {
    border-radius: 10px;
    padding: 12px 20px;
    font-weight: 500;
    transition: var(--transition);
}

.dropdown-item:hover {
    background: linear-gradient(135deg, var(--primary-light) 0%, var(--accent) 100%);
    color: var(--text-white);
}

/* ============================================================
   Hero Section - Full Screen Impact
   ============================================================ */
.hero-section {
    position: relative;
    height: 85vh;
    min-height: 600px;
    background-size: cover;
    background-position: center;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: var(--text-white);
    overflow: hidden;
}

.hero-section::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, rgba(26, 58, 82, 0.85) 0%, rgba(91, 192, 222, 0.75) 50%, rgba(152, 221, 202, 0.65) 100%);
    z-index: 1;
}

.hero-content {
    position: relative;
    z-index: 2;
    max-width: 1000px;
    padding: 0 30px;
    animation: fadeInUp 1s ease;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(40px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.hero-title {
    font-size: clamp(42px, 5vw, 72px);
    font-weight: 900;
    margin-bottom: 25px;
    line-height: 1.1;
    letter-spacing: -2px;
    text-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
}

.hero-subtitle {
    font-size: clamp(18px, 2.5vw, 26px);
    font-weight: 300;
    margin-bottom: 45px;
    opacity: 0.98;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
}

.hero-buttons {
    display: flex;
    gap: 20px;
    justify-content: center;
    flex-wrap: wrap;
}

/* ============================================================
   Buttons - Modern Gradient
   ============================================================ */
.btn {
    display: inline-block;
    padding: 18px 42px;
    border-radius: 50px;
    font-weight: 700;
    font-size: 16px;
    transition: var(--transition);
    cursor: pointer;
    border: none;
    text-transform: uppercase;
    letter-spacing: 1px;
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
    color: var(--text-white) !important;
}

.btn-primary:hover {
    transform: translateY(-4px);
    box-shadow: 0 15px 40px rgba(44, 95, 141, 0.4);
    color: var(--text-white) !important;
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.15);
    backdrop-filter: blur(10px);
    color: var(--text-white) !important;
    border: 2px solid rgba(255, 255, 255, 0.5);
}

.btn-secondary:hover {
    background: var(--text-white);
    color: var(--primary) !important;
    transform: translateY(-4px);
    box-shadow: 0 15px 40px rgba(255, 255, 255, 0.3);
}

/* ============================================================
   Content Sections - Clean Layout
   ============================================================ */
.content-section {
    padding: 120px 0;
}

.section-title {
    font-size: clamp(32px, 4vw, 52px);
    font-weight: 900;
    text-align: center;
    margin-bottom: 80px;
    color: var(--text-dark);
    letter-spacing: -2px;
    line-height: 1.1;
}

/* ============================================================
   Cards - Modern Glassmorphism
   ============================================================ */
.card {
    background: var(--bg-white);
    border-radius: 24px;
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: var(--transition);
    border: 1px solid var(--border-color);
}

.card:hover {
    transform: translateY(-12px);
    box-shadow: var(--shadow-hover);
    border-color: var(--primary-light);
}

.card-image {
    height: 320px;
    overflow: hidden;
    position: relative;
}

.card-image::after {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(to bottom, transparent 0%, rgba(0, 0, 0, 0.1) 100%);
}

.card-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

.card:hover .card-image img {
    transform: scale(1.15);
}

.card-content {
    padding: 35px;
}

.card-title {
    font-size: 26px;
    font-weight: 800;
    margin-bottom: 15px;
    color: var(--text-dark);
    letter-spacing: -0.5px;
}

.card-excerpt {
    color: var(--text-light);
    margin-bottom: 25px;
    line-height: 1.7;
    font-size: 16px;
}

.card-tags {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
    margin-bottom: 25px;
}

.tag {
    background: linear-gradient(135deg, var(--primary-light) 0%, var(--accent) 100%);
    color: var(--text-white);
    padding: 8px 20px;
    border-radius: 30px;
    font-size: 13px;
    font-weight: 700;
    box-shadow: 0 4px 15px rgba(91, 192, 222, 0.3);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* ============================================================
   Page Header Background - Elegant
   ============================================================ */
.page-header-bg {
    position: relative;
    height: 450px;
    background-size: cover;
    background-position: center;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: var(--text-white);
    overflow: hidden;
    margin-bottom: 0;
}

.page-header-bg::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, rgba(26, 58, 82, 0.85) 0%, rgba(91, 192, 222, 0.75) 100%);
}

.page-header-content {
    position: relative;
    z-index: 2;
    max-width: 900px;
    padding: 0 30px;
}

.page-header-content h1 {
    font-size: clamp(36px, 5vw, 62px);
    font-weight: 900;
    margin-bottom: 20px;
    letter-spacing: -2px;
    text-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
}

.page-header-content .breadcrumb {
    background: transparent;
    margin-bottom: 25px;
    justify-content: center;
}

.page-header-content .breadcrumb-item a {
    color: rgba(255, 255, 255, 0.9);
    font-weight: 600;
}

.page-header-content .breadcrumb-item.active {
    color: rgba(255, 255, 255, 0.7);
}

/* ============================================================
   Page Layout - Clean Two Column
   ============================================================ */
.page-layout {
    display: grid;
    grid-template-columns: 1fr 400px;
    gap: 80px;
    padding: 80px 30px;
    max-width: 1600px;
    margin: 0 auto;
}

.page-content {
    background: var(--bg-white);
}

.page-content h1 {
    font-size: clamp(32px, 4vw, 48px);
    font-weight: 900;
    margin-bottom: 30px;
    color: var(--text-dark);
    letter-spacing: -1.5px;
    line-height: 1.2;
}

.page-content h2 {
    font-size: clamp(26px, 3vw, 36px);
    font-weight: 800;
    margin: 60px 0 30px;
    color: var(--text-dark);
    letter-spacing: -1px;
}

.page-content h3 {
    font-size: 24px;
    font-weight: 700;
    margin: 40px 0 20px;
    color: var(--text-dark);
}

.page-content p {
    margin-bottom: 25px;
    color: var(--text-medium);
    line-height: 1.9;
    font-size: 17px;
}

.page-content ul,
.page-content ol {
    margin: 30px 0 30px 40px;
    color: var(--text-medium);
}

.page-content li {
    margin-bottom: 15px;
    line-height: 1.8;
}

/* ============================================================
   Sidebar - Modern Widget
   ============================================================ */
.sidebar {
    position: sticky;
    top: 100px;
    height: fit-content;
}

.sidebar-widget {
    background: var(--bg-white);
    border-radius: 24px;
    padding: 35px;
    margin-bottom: 40px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
}

.widget-title {
    font-size: 22px;
    font-weight: 800;
    margin-bottom: 30px;
    color: var(--text-dark);
    padding-bottom: 20px;
    border-bottom: 3px solid var(--primary-light);
    letter-spacing: -0.5px;
}

/* ============================================================
   Ad Spaces - Subtle Integration
   ============================================================ */
.ad-space {
    background: linear-gradient(135deg, #f7fafc 0%, #edf2f7 100%);
    border: 2px dashed var(--border-color);
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-light);
    font-size: 14px;
    margin: 50px 0;
    min-height: 120px;
}

.ad-banner {
    width: 100%;
    height: 120px;
}

.ad-sidebar {
    width: 100%;
    min-height: 300px;
}

.ad-article {
    width: 100%;
    height: 300px;
}

/* ============================================================
   Forms - Modern Input Fields
   ============================================================ */
.form-group {
    margin-bottom: 30px;
}

.form-label {
    display: block;
    margin-bottom: 12px;
    font-weight: 700;
    color: var(--text-dark);
    font-size: 15px;
    letter-spacing: -0.3px;
}

.form-input,
.form-textarea,
.form-select {
    width: 100%;
    padding: 16px 20px;
    border: 2px solid var(--border-color);
    border-radius: 14px;
    font-size: 16px;
    transition: var(--transition);
    background: var(--bg-white);
    font-family: inherit;
}

.form-input:focus,
.form-textarea:focus,
.form-select:focus {
    outline: none;
    border-color: var(--primary-light);
    box-shadow: 0 0 0 5px rgba(91, 192, 222, 0.15);
}

.form-textarea {
    min-height: 150px;
    resize: vertical;
}

.form-submit {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
    color: var(--text-white);
    padding: 18px 45px;
    border: none;
    border-radius: 50px;
    font-size: 17px;
    font-weight: 800;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: 0 8px 25px rgba(44, 95, 141, 0.3);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.form-submit:hover {
    transform: translateY(-4px);
    box-shadow: 0 15px 40px rgba(44, 95, 141, 0.4);
}

/* ============================================================
   Footer - Dark Modern
   ============================================================ */
.site-footer {
    background: linear-gradient(135deg, var(--primary-dark) 0%, var(--primary) 100%);
    color: var(--text-white);
    padding: 100px 0 50px;
    margin-top: 100px;
}

.footer-widget h5 {
    font-size: 20px;
    font-weight: 800;
    margin-bottom: 25px;
    color: var(--text-white);
    letter-spacing: -0.5px;
}

.footer-widget p,
.footer-widget a {
    color: rgba(255, 255, 255, 0.8);
    line-height: 1.8;
    font-size: 15px;
}

.footer-widget a:hover {
    color: var(--text-white);
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.15);
    margin-top: 60px;
    padding-top: 40px;
}

/* ============================================================
   Responsive Design
   ============================================================ */
@media (max-width: 1024px) {
    .page-layout {
        grid-template-columns: 1fr;
        gap: 50px;
    }
    
    .sidebar {
        position: static;
    }
}

@media (max-width: 768px) {
    .hero-title {
        font-size: 36px;
    }
    
    .hero-subtitle {
        font-size: 18px;
    }
    
    .section-title {
        font-size: 32px;
    }
    
    .btn {
        padding: 15px 35px;
        font-size: 14px;
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
}

/* ============================================================
   Utility Classes
   ============================================================ */
.text-gradient {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hover-lift {
    transition: var(--transition);
}

.hover-lift:hover {
    transform: translateY(-8px);
}

.section-divider {
    height: 4px;
    width: 100px;
    background: linear-gradient(90deg, var(--primary) 0%, var(--primary-light) 100%);
    margin: 40px auto;
    border-radius: 2px;
}