/* ============================================
   YQT Official Website - Main Stylesheet
   Version: 1.0.0
   Author: YQT Technology
   ============================================ */

/* CSS Variables for Theme */
:root {
    --primary-color: #667eea;
    --primary-dark: #5568d3;
    --secondary-color: #764ba2;
    --accent-color: #f093fb;
    --text-primary: #2d3748;
    --text-secondary: #718096;
    --bg-light: #f7fafc;
    --bg-white: #ffffff;
    --border-color: #e2e8f0;
    --success-color: #48bb78;
    --warning-color: #ed8936;
    --danger-color: #f56565;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 40px rgba(0, 0, 0, 0.15);
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
    --border-radius: 8px;
    --border-radius-lg: 12px;
    --max-width: 1200px;
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

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

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

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

ul, ol {
    list-style: none;
}

button {
    border: none;
    background: none;
    cursor: pointer;
    font-family: inherit;
}

input, textarea, select {
    font-family: inherit;
    font-size: inherit;
}

/* Container */
.container {
    width: 100%;
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 20px;
}

/* ============================================
   Header & Navigation
   ============================================ */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
    transition: all var(--transition-normal);
}

.header.scrolled {
    box-shadow: var(--shadow-md);
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
}

.logo a {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo-text {
    font-size: 1.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 2rem;
}

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

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    transition: width var(--transition-normal);
}

.nav-menu a:hover::after,
.nav-menu a.active::after {
    width: 100%;
}

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    padding: 0.5rem;
}

.mobile-menu-toggle span {
    width: 25px;
    height: 3px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: all var(--transition-normal);
}

/* ============================================
   导航下拉菜单（平台能力）
   ============================================ */
.nav-dropdown { position: relative; }
.nav-dropdown > a { cursor: pointer; display: flex; align-items: center; gap: 4px; }
.nav-dropdown .caret { font-size: 0.7em; line-height: 1; transition: transform var(--transition-normal); }
.nav-dropdown:hover .caret,
.nav-dropdown:focus-within .caret { transform: rotate(180deg); }
.nav-dropdown-menu {
    position: absolute; top: 100%; left: 0; min-width: 190px;
    background: #fff; border-radius: 10px; padding: 8px 0;
    box-shadow: 0 12px 32px rgba(102,126,234,.18);
    opacity: 0; visibility: hidden; transform: translateY(10px);
    transition: all var(--transition-normal); z-index: 1100;
    list-style: none;
}
.nav-dropdown:hover .nav-dropdown-menu,
.nav-dropdown:focus-within .nav-dropdown-menu { opacity: 1; visibility: visible; transform: translateY(0); }
.nav-dropdown-menu li { display: block; }
.nav-dropdown-menu a {
    display: block; padding: 9px 20px; color: var(--text-primary);
    font-size: 14px; white-space: nowrap; font-weight: 500;
}
.nav-dropdown-menu a::after { display: none; }
.nav-dropdown-menu a:hover { background: #f4f5ff; color: var(--primary-color); }

/* ============================================
   Hero Section
   ============================================ */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 120px 0 80px;
    overflow: hidden;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    z-index: -2;
}

.gradient-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(circle at 30% 50%, rgba(255, 255, 255, 0.1) 0%, transparent 50%);
}

.particles {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    overflow: hidden;
}

.hero-content {
    text-align: center;
    color: white;
    max-width: 900px;
    margin: 0 auto;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 1.5rem;
}

.hero-title .highlight {
    background: linear-gradient(90deg, #ffd89b 0%, #ff9a9e 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.25rem;
    opacity: 0.9;
    margin-bottom: 2.5rem;
    line-height: 1.8;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-bottom: 3rem;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 4rem;
    margin-top: 3rem;
}

.stat-item {
    text-align: center;
}

.stat-number {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
}

.stat-label {
    font-size: 1rem;
    opacity: 0.8;
}

.scroll-indicator {
    position: absolute;
    bottom: 40px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    color: white;
    opacity: 0.7;
    animation: bounce 2s infinite;
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% {
        transform: translateX(-50%) translateY(0);
    }
    40% {
        transform: translateX(-50%) translateY(-10px);
    }
    60% {
        transform: translateX(-50%) translateY(-5px);
    }
}

/* ============================================
   Buttons
   ============================================ */
.btn {
    display: inline-block;
    padding: 0.875rem 2rem;
    font-size: 1rem;
    font-weight: 600;
    border-radius: var(--border-radius);
    transition: all var(--transition-normal);
    cursor: pointer;
    text-align: center;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(102, 126, 234, 0.5);
}

.btn-outline {
    background: transparent;
    color: white;
    border: 2px solid white;
}

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

.btn-lg {
    padding: 1rem 2.5rem;
    font-size: 1.125rem;
}

.btn-block {
    width: 100%;
}

/* ============================================
   Sections Common Styles
   ============================================ */
section {
    padding: 80px 0;
}

.section-header {
    text-align: center;
    margin-bottom: 4rem;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.section-subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
}

/* ============================================
   Features Section
   ============================================ */
.features {
    background: var(--bg-light);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.feature-card {
    background: white;
    padding: 2.5rem;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-normal);
}

.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-xl);
}

.feature-icon {
    width: 64px;
    height: 64px;
    margin-bottom: 1.5rem;
}

.feature-title {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.feature-description {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    line-height: 1.8;
}

.feature-list {
    margin-bottom: 1.5rem;
}

.feature-list li {
    padding: 0.5rem 0;
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.feature-link {
    color: var(--primary-color);
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: gap var(--transition-fast);
}

.feature-link:hover {
    gap: 0.75rem;
}

/* ============================================
   Solutions Section
   ============================================ */
.solutions-tabs {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.tab-btn {
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    background: white;
    color: var(--text-secondary);
    transition: all var(--transition-fast);
}

.tab-btn:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.tab-btn.active {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border-color: transparent;
    color: white;
}

.solution-panel {
    display: none;
}

.solution-panel.active {
    display: block;
    animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.solution-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
}

.solution-info h3 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.solution-desc {
    color: var(--text-secondary);
    margin-bottom: 2rem;
    line-height: 1.8;
}

.solution-features {
    margin-bottom: 2rem;
}

.solution-features li {
    padding: 0.5rem 0;
    color: var(--text-secondary);
    line-height: 1.8;
}

.solution-image {
    display: flex;
    justify-content: center;
    align-items: center;
}

.image-placeholder {
    width: 100%;
    max-width: 400px;
    border-radius: var(--border-radius-lg);
    overflow: hidden;
}

/* ============================================
   Advantages Section
   ============================================ */
.advantages {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.advantages .section-title,
.advantages .section-subtitle {
    color: white;
}

.advantages-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.advantage-item {
    padding: 2rem;
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border-radius: var(--border-radius-lg);
    border: 1px solid rgba(255, 255, 255, 0.2);
    transition: all var(--transition-normal);
}

.advantage-item:hover {
    background: rgba(255, 255, 255, 0.15);
    transform: translateY(-5px);
}

.advantage-number {
    font-size: 3rem;
    font-weight: 800;
    opacity: 0.3;
    margin-bottom: 1rem;
}

.advantage-item h3 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.advantage-item p {
    opacity: 0.9;
    line-height: 1.8;
}

/* ============================================
   Contact Section
   ============================================ */
.contact-wrapper {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: start;
}

.contact-info h2 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.contact-info > p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
    font-size: 1.125rem;
}

.contact-details {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.contact-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
}

.contact-item svg {
    flex-shrink: 0;
    color: var(--primary-color);
}

.contact-item strong {
    display: block;
    margin-bottom: 0.25rem;
    color: var(--text-primary);
}

.contact-item p {
    color: var(--text-secondary);
}

.contact-form-wrapper {
    background: white;
    padding: 2.5rem;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-lg);
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--text-primary);
}

/* 必填标记样式 */
.form-group label .required {
    color: var(--danger-color);
    margin-left: 2px;
    font-weight: 700;
}

/* 必填标记样式 */
.form-group label .required {
    color: var(--danger-color);
    margin-left: 2px;
    font-weight: 700;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 0.875rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: border-color var(--transition-fast);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

.form-group textarea {
    resize: vertical;
    min-height: 120px;
}

/* ============================================
   Footer
   ============================================ */
.footer {
    background: var(--text-primary);
    color: white;
    padding: 60px 0 30px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 3rem;
    margin-bottom: 3rem;
}

.footer-section h3 {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
}

.footer-section p {
    opacity: 0.8;
    line-height: 1.8;
}

.footer-section ul li {
    margin-bottom: 0.75rem;
}

.footer-section ul li a {
    opacity: 0.8;
    transition: opacity var(--transition-fast);
}

.footer-section ul li a:hover {
    opacity: 1;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    opacity: 0.7;
}

.icp-info {
    margin-top: 0.5rem;
    font-size: 0.875rem;
    opacity: 0.6;
}

/* ============================================
   Responsive Design
   ============================================ */
@media (max-width: 1024px) {
    .hero-title {
        font-size: 2.5rem;
    }
    
    .solution-grid {
        grid-template-columns: 1fr;
    }
    
    .contact-wrapper {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .mobile-menu-toggle {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        top: 70px;
        left: 0;
        right: 0;
        background: white;
        flex-direction: column;
        padding: 2rem;
        box-shadow: var(--shadow-lg);
        transform: translateY(-150%);
        transition: transform var(--transition-normal);
    }
    
    .nav-menu.active {
        transform: translateY(0);
    }

    .nav-dropdown-menu {
        position: static; opacity: 1; visibility: visible; transform: none;
        box-shadow: none; padding: 0 0 0 16px; background: #fafbff; min-width: 0;
    }
    .nav-dropdown > a { justify-content: flex-start; }
    .nav-dropdown .caret { transform: rotate(0); }

    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .hero-buttons {
        flex-direction: column;
    }
    
    .hero-stats {
        flex-direction: column;
        gap: 2rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .features-grid,
    .advantages-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }
    
    section {
        padding: 60px 0;
    }
    
    .hero {
        padding: 100px 0 60px;
    }
    
    .feature-card {
        padding: 1.5rem;
    }
}

/* ============================================
   Utility Classes
   ============================================ */
.text-center {
    text-align: center;
}

.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; }