.left_menu{
    font-family: -apple-system,BlinkMacSystemFont,opensans,Optima,"Microsoft Yahei",sans-serif;
    /*float: left;*/
    width: 20%;
    height: 240px;
    background-color: #ffffff;
    /*margin: 20px auto;*/
    margin-top:50px; 
    margin-left: 1.5%;
    border:1px solid rgba(192,192,192,0.3);
    transition: all 0.5s;
    border-radius: 5px;
    position:fixed;
    text-align: center;
}
.left_menu:hover {
    box-shadow: 2px 5px 10px 1px rgba(192,192,192,0.5);
}
.right_menu{
    font-family: -apple-system,BlinkMacSystemFont,opensans,Optima,"Microsoft Yahei",sans-serif;
    /*float: right;*/
    width: 20%;
    height: 240px;
    background-color: #ffffff;
    /*margin: 20px auto;*/
    margin-top:50px; 
    margin-left: 78.5%;
    border:1px solid rgba(192,192,192,0.3);
    transition: all 0.5s;
    border-radius: 5px;
    position:fixed;
    text-align: center;
}
.right_menu:hover {
    box-shadow: 2px 5px 10px 1px rgba(192,192,192,0.5);
}
.right_menu h3, .left_menu h3{
    text-align: center;
    color: #99CCFF;
    padding-bottom: 20px;
}
.main{
    /*height: 1600px;*/
}
a{
    text-decoration: none;
    text-align: center;
    margin:0px auto;
}