body{background-color: #dff2fc}
#div_title{width: 100%; height: 50px; background-color: #409EFF;
    color: white; font-size: 20px; line-height: 50px; text-align: center}
#table_btn{margin-top: 100px;}
#a_1, #a_2{width: 200px; height: 100px; line-height: 100px; font-size: 16px}