body {
    margin: 0; 
    padding: 0; 
    font: 14px "Microsoft YaHei", sans-serif;
    background: #f5f5f5;
    color: #333;
}

div, dl, dt, dd, ul, ol, li, h1, h2, h3, h4, h5, h6, pre, form, fieldset, input, textarea, blockquote, p {
    padding: 0; 
    margin: 0;
}

a {
    text-decoration: none;
    color: #333;
}

a:hover {
    color: #06c;
}

.header {
    background-color: #3498db;
    width: 100%;
    height: 100px;
    margin: 0 ;
    color: white;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 0 20px;
    box-sizing: border-box;
    position: fixed;
    top: 0;
    left: 0;
    z-index: 200;
}
.header-content {
    width: 1200px;  /* 内部内容限制宽度 */
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 28px;
    font-weight: bold;
}

.nav ul {
    display: flex;
    list-style: none;
}

.nav ul li {
    margin-left: 20px;
}

.nav ul li a {
    color: white;
    font-size: 16px;
}

.nav ul li a:hover {
    color: #f1c40f;
}

.content {
    width: 100%;
    height: auto;
    margin: 100px auto;
    background-color: white;
    overflow: hidden;
    padding: 20px 0;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
    justify-content: center;  /* 内容居中 */
}
.content-inner {
    width: 1200px;
    margin: 0 auto; /* 确保内容居中 */
    position: relative;
    display: flex; /* 使用flex布局 */
}
.left, .right {
    width: 200px;
    height: auto;
    padding: 10px;
    box-sizing: border-box;
}

.left {
    position: fixed;
    left:  calc(50% - 50%);
    top: 100px; /* 与header高度相同 */
    width: 200px;
    height: auto;
    max-height: calc(100vh - 100px); /* 设置最大高度 */
    background-color: #f8f9fa;
    overflow-y: auto; /* 如果内容过多可以滚动 */
    z-index: 100;

}

.right {
    position: fixed;
    right:  calc(50% - 50%);
    top: 100px; /* 与header高度相同 */
    width: 200px;
    height: auto;
    max-height: calc(100vh - 100px); /* 设置最大高度 */
    background-color: #f8f9fa;
    overflow-y: auto; /* 如果内容过多可以滚动 */
    z-index: 100;
}

.center {
    flex: 1; /* 占据剩余空间 */
    margin: 0 auto; /* 左右留出侧边栏空间 */
    padding: 0 20px;
    min-height: calc(100vh - 140px); /* 最小高度，减去header和底部间距 */
}

.sidebar-title {
    font-size: 18px;
    font-weight: bold;
    padding: 10px 0;
    border-bottom: 1px solid #ddd;
    margin-bottom: 10px;
    color: #3498db;
}

.sidebar-menu {
    list-style: none;
    margin-bottom: 20px;
}

.sidebar-menu li {
    padding: 8px 0;
    border-bottom: 1px dashed #eee;
}

.sidebar-menu li a:hover {
    color: #e74c3c;
}

.banner {
    background-color: #3498db;
    color: white;
    width: 1120px;
    padding: 20px;
    margin-bottom: 20px;
    border-radius: 5px;
    text-align: center;
}

.banner h2 {
    font-size: 24px;
    margin-bottom: 10px;
}

.software-section, .study-section {
    margin-bottom: 30px;
}

.software-section h3, .study-section h3 {
    font-size: 20px;
    padding-bottom: 10px;
    border-bottom: 1px solid #eee;
    margin-bottom: 15px;
    color: #2c3e50;
}

.software-list, .study-list {
    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
}

.software-item {
    width: 30%;
    background: #f8f9fa;
    padding: 15px;
    box-sizing: border-box;
    margin-bottom: 20px;
    text-align: center;
    border-radius: 5px;
    transition: all 0.3s;
}

.software-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

.software-item img {
    width: 80px;
    height: 80px;
    margin-bottom: 10px;
}

.software-item h4 {
    font-size: 16px;
    margin-bottom: 5px;
}

.software-item p {
    font-size: 12px;
    color: #777;
    margin-bottom: 10px;
}

.download-btn {
    display: inline-block;
    background: #2ecc71;
    color: white;
    padding: 5px 15px;
    border-radius: 3px;
    font-size: 12px;
}

.download-btn:hover {
    background: #27ae60;
}

.study-item {
    width: 30%;
    background: #f8f9fa;
    padding: 15px;
    box-sizing: border-box;
    margin-bottom: 20px;
    border-radius: 5px;
    transition: all 0.3s;
}

.study-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

.study-item h4 {
    font-size: 16px;
    margin-bottom: 5px;
    color: #3498db;
}

.study-item p {
    font-size: 12px;
    color: #777;
    margin-bottom: 10px;
}

.view-btn {
    display: inline-block;
    background: #3498db;
    color: white;
    padding: 5px 15px;
    border-radius: 3px;
    font-size: 12px;
}

.view-btn:hover {
    background: #2980b9;
}

.notice p, .contact p {
    font-size: 12px;
    padding: 5px 0;
    color: #555;
}

.bottom {
    background-color: #2c3e50;
    width: 100%;
    height: auto;
    margin: 0 auto;
    color: white;
    padding: 20px;
    box-sizing: border-box;
    text-align: center;
    display: flex;
     justify-content: center;  /* 内容居中 */
}
.bottom-content {
    width: 1200px;  /* 内部内容限制宽度 */
}
.footer-links {
    margin-bottom: 10px;
}

.footer-links a {
    color: #bdc3c7;
    margin: 0 10px;
}

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

.copyright {
    font-size: 12px;
    color: #bdc3c7;
}