/* ============================================
   WhatsApp Website - SEO Optimized Stylesheet
   ============================================ */

/* CSS 变量定义 */
:root {
    --primary-color: #25D366;
    --primary-dark: #128C7E;
    --primary-light: #DCF8C6;
    --secondary-color: #075E54;
    --text-primary: #111B21;
    --text-secondary: #667781;
    --text-light: #8696A0;
    --bg-primary: #FFFFFF;
    --bg-secondary: #F0F2F5;
    --bg-tertiary: #F7F8FA;
    --border-color: #E9EDEF;
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.12);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --transition: all 0.3s ease;
}

/* 重置样式 */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* HTML 和 Body */
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-primary);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* 无障碍样式 */
.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--primary-color);
    color: white;
    padding: 8px 16px;
    z-index: 1000;
    transition: var(--transition);
}

.skip-link:focus {
    top: 0;
}

/* 容器 */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ============================================
   头部导航
   ============================================ */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
}

.navbar {
    padding: 12px 0;
}

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

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    text-decoration: none;
    color: var(--text-primary);
}

.logo-icon {
    width: 36px;
    height: 36px;
}

.logo-text {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--secondary-color);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 32px;
}

.nav-menu a {
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    transition: var(--transition);
    position: relative;
}

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: var(--transition);
}

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

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

/* 移动端菜单按钮 */
.mobile-menu-btn {
    display: none;
    width: 40px;
    height: 40px;
    background: none;
    border: none;
    cursor: pointer;
    position: relative;
}

.hamburger,
.hamburger::before,
.hamburger::after {
    width: 24px;
    height: 2px;
    background: var(--text-primary);
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    transition: var(--transition);
}

.hamburger {
    top: 50%;
    transform: translate(-50%, -50%);
}

.hamburger::before {
    content: '';
    top: -8px;
}

.hamburger::after {
    content: '';
    top: 8px;
}

/* ============================================
   面包屑导航
   ============================================ */
.breadcrumb {
    background: var(--bg-secondary);
    padding: 12px 0;
    margin-top: 68px;
}

.breadcrumb ol {
    display: flex;
    list-style: none;
    gap: 8px;
    font-size: 0.875rem;
}

.breadcrumb li:not(:last-child)::after {
    content: '/';
    margin-left: 8px;
    color: var(--text-light);
}

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

.breadcrumb a:hover {
    text-decoration: underline;
}

.breadcrumb span {
    color: var(--text-secondary);
}

/* ============================================
   英雄区域
   ============================================ */
.hero {
    padding: 80px 0 100px;
    background: linear-gradient(135deg, #F0F2F5 0%, #FFFFFF 50%, #DCF8C6 100%);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(37, 211, 102, 0.1) 0%, transparent 70%);
    border-radius: 50%;
}

.hero-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

.hero-content {
    position: relative;
    z-index: 1;
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    line-height: 1.2;
    color: var(--text-primary);
    margin-bottom: 24px;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 32px;
    line-height: 1.7;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    margin-bottom: 24px;
}

.hero-note {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-secondary);
    font-size: 0.875rem;
}

.hero-note svg {
    color: var(--primary-color);
}

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

.phone-mockup {
    max-width: 280px;
    animation: float 6s ease-in-out infinite;
}

.phone-mockup img {
    width: 100%;
    height: auto;
    filter: drop-shadow(0 20px 40px rgba(0, 0, 0, 0.15));
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-20px); }
}

/* 按钮样式 */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 14px 28px;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 600;
    text-decoration: none;
    border: none;
    cursor: pointer;
    transition: var(--transition);
}

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

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

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

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

.btn-large {
    padding: 16px 32px;
    font-size: 1.125rem;
}

.btn-full {
    width: 100%;
}

.btn-platform {
    background: var(--primary-color);
    color: white;
    padding: 12px 24px;
    border-radius: var(--radius-md);
    font-weight: 600;
}

.btn-platform:hover {
    background: var(--primary-dark);
}

/* ============================================
   通用区域标题
   ============================================ */
.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-header-left {
    text-align: left;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 16px;
}

.section-subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

.section-header-left .section-subtitle {
    margin: 0;
}

/* ============================================
   功能特点
   ============================================ */
.features {
    padding: 100px 0;
    background: var(--bg-primary);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
}

.feature-card {
    background: var(--bg-secondary);
    padding: 32px;
    border-radius: var(--radius-lg);
    transition: var(--transition);
    border: 1px solid transparent;
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
    background: white;
}

.feature-icon {
    width: 72px;
    height: 72px;
    background: white;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 20px;
    box-shadow: var(--shadow-sm);
}

.feature-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 12px;
}

.feature-description {
    color: var(--text-secondary);
    line-height: 1.7;
}

/* ============================================
   下载区域
   ============================================ */
.download {
    padding: 100px 0;
    background: var(--bg-tertiary);
}

.download-platforms {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
}

.platform-card {
    background: white;
    padding: 40px 24px;
    border-radius: var(--radius-lg);
    text-align: center;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    border: 2px solid transparent;
}

.platform-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: var(--primary-color);
}

.platform-icon {
    margin-bottom: 20px;
}

.platform-name {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.platform-version {
    color: var(--text-light);
    font-size: 0.875rem;
    margin-bottom: 20px;
}

/* ============================================
   安全隐私
   ============================================ */
.security {
    padding: 100px 0;
    background: linear-gradient(135deg, var(--secondary-color) 0%, var(--primary-dark) 100%);
    color: white;
}

.security-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

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

.security-features {
    display: grid;
    gap: 24px;
}

.security-item {
    display: flex;
    gap: 16px;
    padding: 24px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    backdrop-filter: blur(10px);
}

.security-icon {
    flex-shrink: 0;
    width: 48px;
    height: 48px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
}

.security-text h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 8px;
}

.security-text p {
    opacity: 0.9;
    line-height: 1.6;
}

/* ============================================
   统计数据
   ============================================ */
.stats {
    padding: 80px 0;
    background: var(--bg-secondary);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 40px;
    text-align: center;
}

.stat-item {
    padding: 20px;
}

.stat-number {
    display: block;
    font-size: 3rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 8px;
}

.stat-label {
    font-size: 1rem;
    color: var(--text-secondary);
}

/* ============================================
   常见问题
   ============================================ */
.faq {
    padding: 100px 0;
    background: var(--bg-primary);
}

.faq-list {
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    margin-bottom: 16px;
    overflow: hidden;
    border: 1px solid transparent;
    transition: var(--transition);
}

.faq-item:hover {
    border-color: var(--primary-color);
}

.faq-item[open] {
    background: white;
    box-shadow: var(--shadow-md);
}

.faq-question {
    padding: 20px 24px;
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--text-primary);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    list-style: none;
}

.faq-question::-webkit-details-marker {
    display: none;
}

.faq-icon {
    transition: transform 0.3s ease;
    color: var(--text-secondary);
}

.faq-item[open] .faq-icon {
    transform: rotate(180deg);
    color: var(--primary-color);
}

.faq-answer {
    padding: 0 24px 20px;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* ============================================
   联系我们
   ============================================ */
.contact {
    padding: 100px 0;
    background: var(--bg-tertiary);
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
}

.contact-info {
    display: flex;
    flex-direction: column;
    gap: 32px;
}

.contact-item {
    display: flex;
    gap: 16px;
}

.contact-item svg {
    flex-shrink: 0;
}

.contact-item h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 4px;
}

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

.social-links {
    display: flex;
    gap: 16px;
    margin-top: 8px;
}

.social-links a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
}

.social-links a:hover {
    text-decoration: underline;
}

/* 联系表单 */
.contact-form {
    background: white;
    padding: 40px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
}

.form-group {
    margin-bottom: 24px;
}

.form-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 14px 16px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-family: inherit;
    transition: var(--transition);
    background: white;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 211, 102, 0.1);
}

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

/* ============================================
   页脚
   ============================================ */
.footer {
    background: var(--secondary-color);
    color: white;
    padding: 60px 0 20px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 40px;
    margin-bottom: 40px;
}

.footer-section h4 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 20px;
}

.footer-section ul {
    list-style: none;
}

.footer-section li {
    margin-bottom: 12px;
}

.footer-section a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: var(--transition);
}

.footer-section a:hover {
    color: white;
    text-decoration: underline;
}

.footer-social {
    display: flex;
    gap: 16px;
}

.footer-social a {
    width: 40px;
    height: 40px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.footer-social a:hover {
    background: var(--primary-color);
    transform: translateY(-2px);
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 20px;
    text-align: center;
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.875rem;
}

/* ============================================
   响应式设计
   ============================================ */
@media (max-width: 1024px) {
    .hero-container {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-buttons {
        justify-content: center;
    }
    
    .hero-note {
        justify-content: center;
    }
    
    .hero-image {
        display: none;
    }
    
    .features-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .download-platforms {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .security-content {
        grid-template-columns: 1fr;
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .contact-content {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 68px;
        left: 0;
        right: 0;
        background: white;
        flex-direction: column;
        padding: 20px;
        gap: 16px;
        box-shadow: var(--shadow-md);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: var(--transition);
    }
    
    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }
    
    .mobile-menu-btn {
        display: block;
    }
    
    .mobile-menu-btn.active .hamburger {
        background: transparent;
    }
    
    .mobile-menu-btn.active .hamburger::before {
        top: 0;
        transform: translateX(-50%) rotate(45deg);
    }
    
    .mobile-menu-btn.active .hamburger::after {
        top: 0;
        transform: translateX(-50%) rotate(-45deg);
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .hero {
        padding: 60px 0 80px;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .hero-buttons {
        flex-direction: column;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .download-platforms {
        grid-template-columns: 1fr;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    .stat-number {
        font-size: 2.5rem;
    }
    
    .contact-form {
        padding: 24px;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .footer-social {
        justify-content: center;
    }
}

/* ============================================
   打印样式
   ============================================ */
@media print {
    .header,
    .breadcrumb,
    .hero-image,
    .btn,
    .contact-form {
        display: none !important;
    }
    
    body {
        color: black;
        background: white;
    }
    
    .hero {
        background: white;
        padding: 20px 0;
    }
    
    .section-title {
        color: black;
    }
}