/* 基础样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Microsoft YaHei', Arial, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f8f9fa;
}

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

/* 导航栏样式 */
.navbar {
    background: linear-gradient(135deg, #2c3e50, #3498db);
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
}

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

.nav-logo h1 {
    color: white;
    font-size: 28px;
    font-weight: bold;
}

.nav-logo span {
    color: #ecf0f1;
    font-size: 12px;
    display: block;
    margin-top: -5px;
}

.nav-menu {
    display: flex;
    list-style: none;
    margin: 0;
    padding: 0;
}

.nav-menu li {
    position: relative;
    margin-left: 30px;
}

.nav-menu a {
    color: white;
    text-decoration: none;
    padding: 20px 0;
    display: block;
    transition: color 0.3s ease;
}

.nav-menu a:hover {
    color: #3498db;
}

/* 下拉菜单 */
.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 0;
    background: white;
    min-width: 200px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all 0.3s ease;
    border-radius: 5px;
}

.dropdown:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-menu li {
    margin: 0;
}

.dropdown-menu a {
    color: #333;
    padding: 12px 20px;
    border-bottom: 1px solid #eee;
}

.dropdown-menu a:hover {
    background: #f8f9fa;
    color: #3498db;
}

/* 主要内容区域 */
main {
    margin-top: 80px;
}

/* 英雄区域 */
.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 100px 0;
    text-align: center;
}

.hero-content h2 {
    font-size: 48px;
    margin-bottom: 20px;
    font-weight: bold;
}

.hero-content p {
    font-size: 20px;
    margin-bottom: 40px;
    opacity: 0.9;
}

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

/* 按钮样式 */
.btn {
    display: inline-block;
    padding: 15px 30px;
    text-decoration: none;
    border-radius: 5px;
    font-weight: bold;
    transition: all 0.3s ease;
    border: 2px solid transparent;
}

.btn-primary {
    background: #3498db;
    color: white;
}

.btn-primary:hover {
    background: #2980b9;
    transform: translateY(-2px);
}

.btn-secondary {
    background: transparent;
    color: white;
    border-color: white;
}

.btn-secondary:hover {
    background: white;
    color: #3498db;
}

.btn-outline {
    background: transparent;
    color: #3498db;
    border-color: #3498db;
}

.btn-outline:hover {
    background: #3498db;
    color: white;
}

/* 演示区域 */
.demo-section {
    padding: 80px 0;
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
}

.demo-section h2 {
    text-align: center;
    font-size: 36px;
    margin-bottom: 20px;
    color: #2c3e50;
    font-weight: bold;
}

.demo-section h2::after {
    content: '';
    display: block;
    width: 80px;
    height: 4px;
    background: linear-gradient(90deg, #3498db, #2980b9);
    margin: 15px auto;
    border-radius: 2px;
}

.ventilation-demo {
    max-width: 1200px;
    margin: 0 auto;
}

.demo-container {
    position: relative;
    background: linear-gradient(135deg, #ffffff 0%, #f8f9fa 100%);
    border-radius: 20px;
    padding: 60px 40px;
    margin-bottom: 50px;
    box-shadow: 0 20px 60px rgba(0,0,0,0.1);
    border: 2px solid rgba(52, 152, 219, 0.1);
    overflow: visible;
    min-height: 400px;
}

.demo-container::before {
    content: '';
    position: absolute;
    top: -2px;
    left: -2px;
    right: -2px;
    bottom: -2px;
    background: linear-gradient(45deg, rgba(52, 152, 219, 0.1), rgba(46, 204, 113, 0.1), rgba(155, 89, 182, 0.1), rgba(52, 152, 219, 0.1));
    border-radius: 22px;
    z-index: -1;
    opacity: 0.5;
}

/* 空气区域 */
.outdoor-air, .indoor-air, .treated-air, .exhaust-air {
    position: absolute;
    text-align: center;
    width: 140px;
    padding: 15px;
    background: rgba(255, 255, 255, 0.9);
    border-radius: 12px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    backdrop-filter: blur(10px);
}

.outdoor-air {
    top: 30px;
    left: 30px;
}

.indoor-air {
    top: 30px;
    right: 30px;
}

.treated-air {
    bottom: 30px;
    right: 30px;
}

.exhaust-air {
    bottom: 30px;
    left: 30px;
}

.outdoor-air h3, .indoor-air h3, .treated-air h3, .exhaust-air h3 {
    font-size: 14px;
    margin-bottom: 15px;
    color: #2c3e50;
    font-weight: bold;
}

/* 温度标签 */
.temperature-label {
    display: inline-block;
    padding: 5px 10px;
    border-radius: 15px;
    font-weight: bold;
    font-size: 12px;
    margin-top: 10px;
}

.temperature-label.cold {
    background: #3498db;
    color: white;
}

.temperature-label.warm {
    background: #e74c3c;
    color: white;
}

.temperature-label.treated {
    background: #27ae60;
    color: white;
}

.temperature-label.exhaust {
    background: #95a5a6;
    color: white;
}

/* 新风机主体 */
.ventilation-unit {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 30px;
    margin: 80px 0;
    position: relative;
    padding: 20px;
}

/* 过滤器 */
.filter {
    width: 70px;
    height: 90px;
    background: linear-gradient(135deg, #34495e, #2c3e50);
    border-radius: 8px;
    position: relative;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    box-shadow: 0 8px 25px rgba(52, 73, 94, 0.3);
    border: 2px solid rgba(236, 240, 241, 0.2);
}

.filter::before {
    content: '';
    position: absolute;
    top: 5px;
    left: 5px;
    right: 5px;
    bottom: 5px;
    border: 1px solid rgba(236, 240, 241, 0.3);
    border-radius: 6px;
}

.filter-layers {
    display: flex;
    flex-direction: column;
    gap: 4px;
    z-index: 2;
}

.filter-layer {
    width: 45px;
    height: 9px;
    background: linear-gradient(90deg, #ecf0f1, #bdc3c7);
    border-radius: 3px;
    box-shadow: inset 0 1px 2px rgba(0,0,0,0.1);
}

.filter-label {
    position: absolute;
    bottom: -35px;
    font-size: 11px;
    color: #2c3e50;
    white-space: nowrap;
    font-weight: 600;
    background: rgba(255, 255, 255, 0.9);
    padding: 4px 8px;
    border-radius: 4px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

/* 热交换器 */
.heat-exchanger {
    width: 140px;
    height: 120px;
    background: linear-gradient(135deg, #e67e22, #d35400);
    border-radius: 12px;
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    box-shadow: 0 10px 30px rgba(230, 126, 34, 0.4);
    border: 3px solid rgba(243, 156, 18, 0.3);
}

.heat-exchanger::after {
    content: '';
    position: absolute;
    top: 8px;
    left: 8px;
    right: 8px;
    bottom: 8px;
    border: 2px solid rgba(255, 255, 255, 0.2);
    border-radius: 8px;
}

.exchanger-core {
    position: relative;
    width: 90px;
    height: 70px;
    z-index: 2;
}

.heat-plates {
    display: flex;
    flex-direction: column;
    gap: 3px;
    height: 100%;
    justify-content: center;
}

.plate {
    height: 10px;
    background: linear-gradient(90deg, #d35400, #e67e22, #d35400);
    border-radius: 3px;
    box-shadow: inset 0 1px 2px rgba(0,0,0,0.2);
}

.exchanger-label {
    position: absolute;
    bottom: -35px;
    font-size: 11px;
    color: #2c3e50;
    white-space: nowrap;
    left: 50%;
    transform: translateX(-50%);
    font-weight: 600;
    background: rgba(255, 255, 255, 0.9);
    padding: 4px 8px;
    border-radius: 4px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.efficiency-display {
    position: absolute;
    top: -35px;
    left: 50%;
    transform: translateX(-50%);
    font-size: 12px;
    color: #e67e22;
    font-weight: bold;
    white-space: nowrap;
    background: rgba(255, 255, 255, 0.95);
    padding: 6px 12px;
    border-radius: 20px;
    box-shadow: 0 4px 15px rgba(230, 126, 34, 0.3);
    border: 2px solid rgba(230, 126, 34, 0.2);
}

/* 风机 */
.fan-unit {
    position: relative;
}

.fan {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, #2c3e50, #34495e);
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
    box-shadow: 0 8px 25px rgba(44, 62, 80, 0.4);
    border: 3px solid rgba(52, 73, 94, 0.3);
}

.fan::before {
    content: '';
    position: absolute;
    width: 60px;
    height: 60px;
    border: 2px solid rgba(236, 240, 241, 0.2);
    border-radius: 50%;
}

.fan-blades {
    width: 50px;
    height: 50px;
    position: relative;
    z-index: 2;
}

.blade {
    position: absolute;
    width: 25px;
    height: 5px;
    background: linear-gradient(90deg, #ecf0f1, #bdc3c7);
    border-radius: 3px;
    top: 50%;
    left: 50%;
    transform-origin: center;
    box-shadow: 0 1px 3px rgba(0,0,0,0.2);
}

.blade:nth-child(1) { transform: translate(-50%, -50%) rotate(0deg); }
.blade:nth-child(2) { transform: translate(-50%, -50%) rotate(90deg); }
.blade:nth-child(3) { transform: translate(-50%, -50%) rotate(180deg); }
.blade:nth-child(4) { transform: translate(-50%, -50%) rotate(270deg); }

.fan-label {
    position: absolute;
    bottom: -35px;
    font-size: 11px;
    color: #2c3e50;
    white-space: nowrap;
    left: 50%;
    transform: translateX(-50%);
    font-weight: 600;
    background: rgba(255, 255, 255, 0.9);
    padding: 4px 8px;
    border-radius: 4px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

/* 排风机单元特殊样式 */
.exhaust-fan-unit {
    margin-left: 20px;
}

.exhaust-fan {
    background: linear-gradient(135deg, #95a5a6, #7f8c8d);
    border-color: rgba(149, 165, 166, 0.3);
    box-shadow: 0 8px 25px rgba(149, 165, 166, 0.4);
}

/* 工作原理说明 */
.demo-explanation {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
    margin-top: 40px;
}

.explanation-item {
    display: flex;
    align-items: flex-start;
    gap: 15px;
    padding: 20px;
    background: white;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

.step-number {
    width: 40px;
    height: 40px;
    background: #3498db;
    color: white;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    font-weight: bold;
    flex-shrink: 0;
}

.step-content h4 {
    color: #2c3e50;
    margin-bottom: 8px;
}

.step-content p {
    color: #7f8c8d;
    font-size: 14px;
}

/* 产品特点 */
.features {
    padding: 80px 0;
    background: #ecf0f1;
}

.features h2 {
    text-align: center;
    font-size: 36px;
    margin-bottom: 50px;
    color: #2c3e50;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.feature-item {
    background: white;
    padding: 40px 30px;
    border-radius: 10px;
    text-align: center;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    transition: transform 0.3s ease;
}

.feature-item:hover {
    transform: translateY(-5px);
}

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

.feature-item h3 {
    color: #2c3e50;
    margin-bottom: 15px;
    font-size: 20px;
}

.feature-item p {
    color: #7f8c8d;
    line-height: 1.6;
}

/* 应用场景 */
.applications {
    padding: 80px 0;
    background: white;
}

.applications h2 {
    text-align: center;
    font-size: 36px;
    margin-bottom: 50px;
    color: #2c3e50;
}

.applications-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
}

.application-item {
    background: white;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    transition: transform 0.3s ease;
}

.application-item:hover {
    transform: translateY(-5px);
}

.application-item img {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.application-item h3 {
    padding: 20px 20px 10px;
    color: #2c3e50;
    font-size: 20px;
}

.application-item p {
    padding: 0 20px 15px;
    color: #7f8c8d;
    line-height: 1.6;
}

.application-item .btn {
    margin: 0 20px 20px;
}

/* 页脚 */
.footer {
    background: #2c3e50;
    color: white;
    padding: 60px 0 20px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
    margin-bottom: 40px;
}

.footer-section h3,
.footer-section h4 {
    margin-bottom: 20px;
    color: #ecf0f1;
}

.footer-section p {
    color: #bdc3c7;
    line-height: 1.6;
    margin-bottom: 10px;
}

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

.footer-section ul li {
    margin-bottom: 8px;
}

.footer-section ul li a {
    color: #bdc3c7;
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-section ul li a:hover {
    color: #3498db;
}

.footer-bottom {
    border-top: 1px solid #34495e;
    padding-top: 20px;
    text-align: center;
    color: #bdc3c7;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .nav-container {
        flex-direction: column;
        padding: 10px 20px;
    }
    
    .nav-menu {
        margin-top: 10px;
        flex-wrap: wrap;
        justify-content: center;
    }
    
    .nav-menu li {
        margin: 5px 15px;
    }
    
    .hero-content h2 {
        font-size: 32px;
    }
    
    .hero-content p {
        font-size: 16px;
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .demo-container {
        padding: 20px;
    }
    
    .ventilation-unit {
        flex-direction: column;
        gap: 15px;
    }
    
    .outdoor-air, .indoor-air, .treated-air, .exhaust-air {
        position: static;
        margin: 10px auto;
    }
    
    .demo-explanation {
        grid-template-columns: 1fr;
    }
    
    .features-grid,
    .applications-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }
    
    .hero {
        padding: 60px 0;
    }
    
    .demo-section,
    .features,
    .applications {
        padding: 40px 0;
    }
    
    .demo-section h2,
    .features h2,
    .applications h2 {
        font-size: 28px;
    }
}