/* ===== 全局样式 ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #0066cc;
    --primary-dark: #0052a3;
    --primary-light: #3399ff;
    --secondary-color: #00b8d4;
    --accent-color: #ff9800;
    --text-primary: #1a1a1a;
    --text-secondary: #666666;
    --text-light: #999999;
    --bg-white: #ffffff;
    --bg-light: #f5f8fa;
    --bg-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.16);
    --border-radius: 12px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

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: var(--bg-white);
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ===== 导航栏 ===== */
.navbar {
    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: var(--transition);
}

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

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 24px;
    font-weight: 700;
    color: var(--primary-color);
    cursor: pointer;
}

.logo-icon {
    font-size: 28px;
}

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

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

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

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

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

.btn-download {
    background: var(--primary-color);
    color: white !important;
    padding: 8px 20px;
    border-radius: 20px;
    transition: var(--transition);
}

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

.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: var(--transition);
}

/* ===== 首页横幅 ===== */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    background: linear-gradient(135deg, #e0f2ff 0%, #f0f9ff 50%, #e8f5e9 100%);
    padding: 100px 20px 60px;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 800px;
    height: 800px;
    background: radial-gradient(circle, rgba(102, 126, 234, 0.1) 0%, transparent 70%);
    border-radius: 50%;
}

.hero::after {
    content: '';
    position: absolute;
    bottom: -30%;
    left: -10%;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(0, 184, 212, 0.1) 0%, transparent 70%);
    border-radius: 50%;
}

.hero-container {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-content {
    animation: fadeInUp 0.8s ease-out;
}

.hero-title {
    font-size: 56px;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 24px;
    color: var(--text-primary);
}

.title-highlight {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 20px;
    color: var(--text-secondary);
    margin-bottom: 40px;
    line-height: 1.8;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 14px 32px;
    border-radius: 30px;
    font-size: 16px;
    font-weight: 600;
    text-decoration: none;
    transition: var(--transition);
    border: none;
    cursor: pointer;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    box-shadow: 0 4px 15px rgba(0, 102, 204, 0.3);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(0, 102, 204, 0.4);
}

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

.btn-secondary:hover {
    background: var(--primary-color);
    color: white;
    transform: translateY(-3px);
}

.hero-visual {
    position: relative;
    height: 500px;
}

.floating-card {
    position: absolute;
    background: white;
    border-radius: 16px;
    padding: 20px 24px;
    box-shadow: var(--shadow-lg);
    display: flex;
    align-items: center;
    gap: 12px;
    animation: float 6s ease-in-out infinite;
}

.card-icon {
    font-size: 32px;
}

.card-text {
    font-size: 18px;
    font-weight: 600;
    color: var(--text-primary);
}

.card-1 {
    top: 10%;
    right: 20%;
    animation-delay: 0s;
}

.card-2 {
    top: 35%;
    right: 5%;
    animation-delay: 1s;
}

.card-3 {
    bottom: 30%;
    right: 25%;
    animation-delay: 2s;
}

.card-4 {
    bottom: 5%;
    right: 10%;
    animation-delay: 3s;
}

.wave-bottom {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    line-height: 0;
}

/* ===== 平台数据 ===== */
.stats-section {
    background: white;
    padding: 60px 20px;
    position: relative;
    z-index: 2;
    margin-top: -60px;
}

.stats-container {
    max-width: 1000px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 30px;
}

.stat-item {
    text-align: center;
    padding: 30px 20px;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
    transition: var(--transition);
}

.stat-item:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.stat-number {
    font-size: 36px;
    font-weight: 800;
    color: var(--primary-color);
    margin-bottom: 8px;
}

.stat-label {
    font-size: 14px;
    color: var(--text-secondary);
}

/* ===== 功能特点 ===== */
.features {
    padding: 100px 20px;
    background: var(--bg-light);
}

.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-title {
    font-size: 40px;
    font-weight: 700;
    margin-bottom: 16px;
    color: var(--text-primary);
}

.section-subtitle {
    font-size: 18px;
    color: var(--text-secondary);
}

.features-grid {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
}

.feature-card {
    background: white;
    padding: 40px 30px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
}

.feature-icon {
    font-size: 48px;
    margin-bottom: 20px;
}

.feature-title {
    font-size: 22px;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.feature-desc {
    font-size: 15px;
    color: var(--text-secondary);
    line-height: 1.8;
}

/* ===== 核心模块 ===== */
.modules {
    padding: 100px 20px;
    background: white;
}

.modules-showcase {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1.5fr 1fr 1fr;
    gap: 30px;
    align-items: stretch;
}

.module-card {
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    padding: 40px;
    border-radius: 20px;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    display: flex;
    flex-direction: column;
}

.module-card.large {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.module-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
}

.module-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 16px;
}

.module-icon {
    font-size: 40px;
}

.module-title {
    font-size: 24px;
    font-weight: 700;
}

.module-desc {
    margin-bottom: 20px;
    opacity: 0.9;
}

.post-types {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 20px;
}

.post-type {
    background: rgba(255, 255, 255, 0.2);
    padding: 6px 12px;
    border-radius: 20px;
    font-size: 13px;
    backdrop-filter: blur(10px);
}

.post-type.highlight {
    background: rgba(255, 255, 255, 0.3);
    font-weight: 600;
}

.module-features {
    list-style: none;
    flex-grow: 1;
}

.module-features li {
    padding: 8px 0;
    font-size: 14px;
    opacity: 0.9;
}

/* ===== 精彩活动 ===== */
.activities {
    padding: 100px 20px;
    background: var(--bg-light);
}

.activities-grid {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
}

.activity-card {
    background: white;
    padding: 40px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    position: relative;
}

.activity-card.featured {
    background: linear-gradient(135deg, #ffa726 0%, #fb8c00 100%);
    color: white;
    grid-column: span 2;
}

.activity-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
}

.activity-badge {
    position: absolute;
    top: 20px;
    right: 20px;
    background: rgba(255, 255, 255, 0.3);
    color: #d84315;
    padding: 6px 12px;
    border-radius: 20px;
    font-size: 12px;
    font-weight: 600;
}

.activity-icon {
    font-size: 48px;
    margin-bottom: 20px;
}

.activity-title {
    font-size: 24px;
    font-weight: 700;
    margin-bottom: 16px;
}

.activity-desc {
    font-size: 15px;
    line-height: 1.8;
    margin-bottom: 20px;
    opacity: 0.9;
}

.activity-rewards {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.reward-item {
    background: rgba(255, 255, 255, 0.15);
    padding: 8px 16px;
    border-radius: 20px;
    font-size: 14px;
}

/* ===== 帖子类型详解 ===== */
.post-details {
    padding: 100px 20px;
    background: white;
}

.post-showcase {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1.5fr 1fr;
    gap: 30px;
}

.post-detail-card {
    background: white;
    border-radius: 20px;
    box-shadow: var(--shadow-md);
    overflow: hidden;
    transition: var(--transition);
}

.post-detail-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
}

.post-detail-card.featured {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.post-badge {
    position: absolute;
    top: 20px;
    right: 20px;
    background: rgba(255, 215, 0, 0.9);
    color: #d84315;
    padding: 6px 12px;
    border-radius: 20px;
    font-size: 12px;
    font-weight: 600;
}

.post-header {
    padding: 40px 40px 20px;
    display: flex;
    align-items: center;
    gap: 16px;
}

.post-icon-large {
    font-size: 48px;
}

.post-title-large {
    font-size: 28px;
    font-weight: 700;
}

.post-content {
    padding: 20px 40px 40px;
}

.post-description {
    font-size: 16px;
    line-height: 1.8;
    margin-bottom: 30px;
    opacity: 0.95;
}

.post-features-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
    margin-bottom: 30px;
}

.feature-item {
    background: rgba(255, 255, 255, 0.1);
    padding: 20px;
    border-radius: 12px;
    display: flex;
    align-items: flex-start;
    gap: 12px;
    backdrop-filter: blur(10px);
}

.feature-icon {
    font-size: 24px;
    flex-shrink: 0;
}

.feature-text h4 {
    font-size: 15px;
    font-weight: 600;
    margin-bottom: 4px;
}

.feature-text p {
    font-size: 13px;
    opacity: 0.9;
    line-height: 1.5;
}

.post-highlights {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.highlight-tag {
    background: rgba(255, 255, 255, 0.2);
    padding: 8px 16px;
    border-radius: 20px;
    font-size: 13px;
    backdrop-filter: blur(10px);
}

.bounty-flow {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 30px;
    gap: 10px;
}

.flow-item {
    flex: 1;
    text-align: center;
    padding: 20px 15px;
    background: var(--bg-light);
    border-radius: 12px;
}

.flow-number {
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 18px;
    font-weight: 700;
    margin: 0 auto 12px;
}

.flow-item h4 {
    font-size: 14px;
    margin-bottom: 6px;
    color: var(--text-primary);
}

.flow-item p {
    font-size: 12px;
    color: var(--text-secondary);
}

.flow-arrow {
    font-size: 24px;
    color: var(--primary-color);
}

.bounty-status {
    background: var(--bg-light);
    padding: 25px;
    border-radius: 16px;
    margin-bottom: 20px;
}

.bounty-status h4 {
    font-size: 16px;
    margin-bottom: 20px;
    color: var(--text-primary);
    font-weight: 600;
}

.status-timeline {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.timeline-item {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    padding: 12px;
    background: white;
    border-radius: 10px;
    transition: var(--transition);
}

.timeline-item:hover {
    transform: translateX(5px);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.timeline-icon {
    width: 40px;
    height: 40px;
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    flex-shrink: 0;
}

.timeline-icon.waiting {
    background: linear-gradient(135deg, #fff3e0 0%, #ffe0b2 100%);
}

.timeline-icon.solved {
    background: linear-gradient(135deg, #e8f5e9 0%, #c8e6c9 100%);
}

.timeline-icon.ended {
    background: linear-gradient(135deg, #e3f2fd 0%, #bbdefb 100%);
}

.timeline-icon.closed {
    background: linear-gradient(135deg, #f5f5f5 0%, #e0e0e0 100%);
}

.timeline-content h5 {
    font-size: 14px;
    font-weight: 600;
    margin-bottom: 4px;
    color: var(--text-primary);
}

.timeline-content p {
    font-size: 13px;
    color: var(--text-secondary);
    line-height: 1.5;
}

.post-features {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.mini-tag {
    background: var(--primary-light);
    color: white;
    padding: 6px 12px;
    border-radius: 15px;
    font-size: 12px;
}

/* ===== 用户等级 ===== */
.levels {
    padding: 100px 20px;
    background: var(--bg-light);
}

.levels-grid {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
    margin-bottom: 40px;
}

.level-item {
    background: white;
    padding: 30px 20px;
    border-radius: var(--border-radius);
    text-align: center;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.level-item:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
}

.level-item.highlight {
    background: linear-gradient(135deg, #ffd89b 0%, #19547b 100%);
    color: white;
}

.level-badge {
    width: 70px;
    height: 70px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 18px;
    font-weight: 700;
    margin: 0 auto 16px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.level-badge.lv1 { background: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%); }
.level-badge.lv2 { background: linear-gradient(135deg, #d299c2 0%, #fef9d7 100%); }
.level-badge.lv3 { background: linear-gradient(135deg, #89f7fe 0%, #66a6ff 100%); }
.level-badge.lv4 { background: linear-gradient(135deg, #fddb92 0%, #d1fdff 100%); }
.level-badge.lv5 { background: linear-gradient(135deg, #96fbc4 0%, #f9f586 100%); }
.level-badge.lv6 { background: linear-gradient(135deg, #cd9cf2 0%, #f6f3ff 100%); }
.level-badge.lv7 { background: linear-gradient(135deg, #fa709a 0%, #fee140 100%); }
.level-badge.lv8 { background: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%); }

.level-range {
    font-size: 13px;
    color: var(--text-secondary);
    margin-bottom: 8px;
}

.level-name {
    font-size: 16px;
    font-weight: 600;
}

.levels-features {
    max-width: 800px;
    margin: 0 auto;
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 15px;
}

.feature-tag {
    background: white;
    padding: 12px 24px;
    border-radius: 25px;
    font-size: 14px;
    box-shadow: var(--shadow-sm);
}

/* ===== 下载引导 ===== */
.download {
    padding: 100px 20px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.download-content {
    max-width: 900px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 60px;
    align-items: center;
}

.download-title {
    font-size: 40px;
    font-weight: 700;
    margin-bottom: 20px;
}

.download-desc {
    font-size: 18px;
    opacity: 0.9;
    margin-bottom: 40px;
    line-height: 1.8;
}

.download-steps {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.step {
    display: flex;
    align-items: center;
    gap: 20px;
}

.step-number {
    width: 50px;
    height: 50px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    font-weight: 700;
}

.step-text {
    font-size: 16px;
}

.download-qr {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.qr-container {
    background: white;
    padding: 30px;
    border-radius: 20px;
    box-shadow: var(--shadow-lg);
}

.qr-placeholder {
    width: 200px;
    height: 200px;
    background: var(--bg-light);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-light);
}

.qr-label {
    margin-top: 16px;
    color: var(--text-primary);
    font-weight: 600;
}

/* ===== 页脚 ===== */
.footer {
    background: #1a1a1a;
    color: white;
    padding: 60px 20px 20px;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1.5fr 2fr;
    gap: 60px;
    margin-bottom: 40px;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 24px;
    font-weight: 700;
    margin-bottom: 16px;
}

.footer-slogan {
    font-size: 14px;
    color: rgba(255, 255, 255, 0.6);
}

.footer-links {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 40px;
}

.footer-column h4 {
    font-size: 16px;
    margin-bottom: 20px;
}

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

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

.footer-column a {
    color: rgba(255, 255, 255, 0.6);
    text-decoration: none;
    transition: var(--transition);
}

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

.footer-bottom {
    max-width: 1200px;
    margin: 0 auto;
    padding-top: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    text-align: center;
}

.copyright {
    color: rgba(255, 255, 255, 0.4);
    font-size: 14px;
    margin-bottom: 12px;
}

.beian-info {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 20px;
    flex-wrap: wrap;
}

.beian-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    color: rgba(255, 255, 255, 0.5);
    text-decoration: none;
    font-size: 13px;
    transition: var(--transition);
    padding: 6px 12px;
    border-radius: 6px;
}

.beian-link:hover {
    color: rgba(255, 255, 255, 0.8);
    background: rgba(255, 255, 255, 0.05);
    transform: translateY(-2px);
}

.beian-icon {
    width: 16px;
    height: 16px;
    vertical-align: middle;
    object-fit: contain;
}

/* ===== 返回顶部按钮 ===== */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    box-shadow: var(--shadow-md);
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    z-index: 999;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    background: var(--primary-dark);
    transform: translateY(-5px);
}

/* ===== 动画效果 ===== */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

/* ===== 响应式设计 ===== */
@media (max-width: 1024px) {
    .hero-title {
        font-size: 48px;
    }

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

    .modules-showcase {
        grid-template-columns: 1fr;
    }

    .module-card.large {
        grid-column: span 1;
    }

    .activity-card.featured {
        grid-column: span 2;
    }

    .levels-grid {
        grid-template-columns: repeat(4, 1fr);
    }

    .post-showcase {
        grid-template-columns: 1fr;
    }

    .bounty-flow {
        flex-direction: column;
    }

    .flow-arrow {
        transform: rotate(90deg);
    }
}

@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 70px;
        left: -100%;
        width: 100%;
        height: calc(100vh - 70px);
        background: white;
        flex-direction: column;
        align-items: center;
        justify-content: center;
        gap: 24px;
        transition: var(--transition);
        box-shadow: var(--shadow-md);
    }

    .nav-menu.active {
        left: 0;
    }

    .hamburger {
        display: flex;
    }

    .hero-container {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .hero-visual {
        display: none;
    }

    .hero-title {
        font-size: 36px;
    }

    .hero-subtitle {
        font-size: 16px;
    }

    .hero-buttons {
        justify-content: center;
    }

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

    .features-grid,
    .activities-grid {
        grid-template-columns: 1fr;
    }

    .activity-card.featured {
        grid-column: span 1;
    }

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

    .post-showcase {
        grid-template-columns: 1fr;
    }

    .post-features-grid {
        grid-template-columns: 1fr;
    }

    .download-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .download-steps {
        align-items: center;
    }

    .footer-content {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .footer-links {
        grid-template-columns: 1fr;
    }

    .beian-info {
        flex-direction: column;
        gap: 12px;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 28px;
    }

    .section-title {
        font-size: 32px;
    }

    .stats-container {
        grid-template-columns: 1fr;
    }

    .stat-number {
        font-size: 28px;
    }

    .btn {
        padding: 12px 24px;
        font-size: 14px;
    }

    .post-header {
        padding: 30px 20px 15px;
    }

    .post-content {
        padding: 15px 20px 30px;
    }
}