.daohl nav {
    width: 100%;
    margin: 0;
    padding: 0;
}
.daohl ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
    overflow: hidden;
    background-color: #333;
}

.daohl li {
    float: left;
}

.daohl li a {
    display: block;
    color: white;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
}

.daohl li a:hover {
    background-color: #111;
}

a{
    text-decoration: none; 
    color: cornflowerblue;
 }


ul {
    list-style-type: none; /* 移除默认的标记 */
    padding: 0;
}

li {
    padding: 5px;
    margin-bottom: 5px;
    
}

ol {
    list-style-type: upper-roman; /* 改变标记为罗马数字 */
}

dt {
    font-weight: bold;
}

dd {
    margin-left: 40px; /* 增加描述的缩进 */
}



.div2-1{
    width: 100%;
    height: 350px;
    background-image: url(../img/socket-class.png);
    background-size: cover;
    background-position: center; 
    background-repeat: no-repeat;
}
.div2-2{
    width: 80%;
    height: 500px;
    background-color: rgba(0, 0, 0, 0.6);
    margin: auto;
    margin-top: 20px;
    color: aliceblue;
    font-size: 200%;
}