#container{
    width:100%;
    margin:0 auto;
    font-size:13px;
}
.cat {
    display:flex;
    flex-direction:column;    
    text-align:center;
    line-height:10px;
    float:left;
}

.cat div{
    border: 1px solid blue;
    padding: 75px;
    width: 125px;
    font-size: 26px;
    text-align: center;
    float:left;
    }

#head{
    height:80px;
    text-align:center;
    line-height:80px;
}
#left{
    height:400px;    
    width:300px;
    text-align:center;
    line-height:400px;
    float:left;
}
#right{
    width:300px;
    height:400px;
    text-align:center;
    line-height:400px;
    float:right;
}
#mid{
    text-orientation: upright;
    margin-left:300px;
    margin-right:300px;
    height:100%;
    text-align:center;
    line-height:100px;
}
#foot{
    clear:both;
    height:80px;
    text-align:center;
    line-height:80px;
}

a:link{
    color: darkcyan;
}
a:visited{
    color: cornflowerblue;
}
a:hover{
    color: darkolivegreen;
}
a:active{
    color: blueviolet;
}

.box-1 {
    flex:1;
}

.box-2 {
    flex:1;
}

.box-3 {
    flex:1;
}

.box-4 {
    flex:1;
}

            body {
                margin: auto;
            }
            
            .dropbtn {
                background-color: #4CAF50;
                color: #fff;
                padding: 16px;
                font-size: 16px;
                border: none;
                cursor: pointer;
            }
            
            .dropdown {
                position: relative;
                display: inline-block;
            }
            
            .dropdown-content {
                /* 隱藏元素 */
                display: none;
                position: absolute;
                background-color: #f9f9f9;
                min-width: 160px;
                box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
            }
            
            .dropdown-content a {
                color: black;
                padding: 12px 16px;
                text-decoration: none;
                display: block;
            }
            
            .dropdown-content a:hover {
                background-color: #f1f1f1
            }
            
            /* .dropdown的hover效果，作用在.dropdown-content上 */
            .dropdown:hover .dropdown-content {
                display: block;
            }
            
            .dropdown:hover .dropbtn {
                background-color: #3dc741;
            }