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

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

/* 基础颜色定义 */
:root {
    --primary-color: #8B4513; /* 大地棕 */
    --secondary-color: #1E90FF; /* 科技蓝 */
    --light-color: #f4f4f4;
    --dark-color: #333;
    --success-color: #28a745;
    --error-color: #dc3545;
}

/* 图片加载失败占位符 */
img {
    display: block;
    width: 100%;
    height: auto;
}

/* 导航栏样式 */
.navbar {
    background-color: var(--primary-color);
    color: white;
    padding: 1rem;
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 1000;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.navbar.scrolled {
    background-color: rgba(139, 69, 19, 0.9);
}

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

.navbar .logo .logo-img {
    max-height: 40px;
    width: auto;
    display: block;
    object-fit: contain;
}



/* 容器样式 */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

/* 企业介绍模块 */
.about {
    padding: 3rem 0;
    background-color: var(--light-color);
    margin-top: 4rem; /* 为固定导航栏预留空间 */
}

.about-content h3 {
    color: var(--primary-color);
    margin: 2rem 0 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--primary-color);
}

.timeline {
    position: relative;
    max-width: 800px;
    margin: 2rem auto;
}

.timeline::after {
    content: '';
    position: absolute;
    width: 4px;
    background-color: var(--primary-color);
    top: 0;
    bottom: 0;
    left: 50%;
    margin-left: -2px;
}

.timeline-item {
    padding: 10px 40px;
    position: relative;
    width: 50%;
    box-sizing: border-box;
}

.timeline-item:nth-child(odd) {
    left: 0;
}

.timeline-item:nth-child(even) {
    left: 50%;
}

.timeline-content {
    padding: 20px;
    background-color: white;
    position: relative;
    border-radius: 6px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

.timeline-content h4 {
    color: var(--primary-color);
    margin-top: 0;
}

.timeline-item:nth-child(odd)::after {
    content: '';
    position: absolute;
    width: 20px;
    height: 20px;
    right: -10px;
    background-color: var(--primary-color);
    border: 4px solid #f1f1f1;
    top: 15px;
    border-radius: 50%;
    z-index: 1;
}

.timeline-item:nth-child(even)::after {
    content: '';
    position: absolute;
    width: 20px;
    height: 20px;
    left: -10px;
    background-color: var(--primary-color);
    border: 4px solid #f1f1f1;
    top: 15px;
    border-radius: 50%;
    z-index: 1;
}

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

.certificate-category {
    background-color: white;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    padding: 1.5rem;
}

.certificate-category h4 {
    color: var(--primary-color);
    margin-top: 0;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.certificate-category ul {
    list-style: none;
    padding-left: 0;
}

.certificate-category li {
    padding: 0.8rem 1rem;
    border-bottom: 1px solid #eee;
    display: flex;
    align-items: center;
    transition: all 0.3s ease;
    border-radius: 4px;
    margin: 0.2rem 0;
}

.certificate-category li:hover {
    background-color: #f8f9fa;
    transform: translateX(5px);
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.certificate-category li:last-child {
    border-bottom: none;
}

.certificate-category li:before {
    content: "•";
    color: var(--primary-color);
    font-weight: bold;
    display: inline-block;
    width: 1em;
    margin-right: 0.8em;
    font-size: 1.2em;
}

/* 页脚样式 */
.footer {
    background-color: var(--primary-color);
    color: white;
    text-align: center;
    padding: 2rem 0;
    margin-top: 3rem;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .container {
        width: 90%;
        padding: 0 1rem;
    }
    
    .navbar .container {
        flex-direction: column;
        align-items: flex-start;
    }
    
    
}

/* 小屏幕设备优化 */
@media (max-width: 480px) {
    .navbar .logo h1 {
        font-size: 1.2rem;
    }
    
    .timeline::after {
        left: 31px;
    }
    
    .timeline-item {
        width: 100%;
        padding-left: 70px;
        padding-right: 25px;
    }
    
    .timeline-item:nth-child(even) {
        left: 0;
    }
    
    .timeline-item:nth-child(odd)::after,
    .timeline-item:nth-child(even)::after {
        left: 21px;
    }
    
    .certificates {
        grid-template-columns: 1fr;
    }
    
    .about {
        margin-top: 5.5rem;
    }
    
    .footer {
        padding: 1rem 0;
        font-size: 0.9rem;
    }
}