bootstrap模態框如何加上捲軸

 .modal-dialog {
            position: absolute;
            top: 0;
            bottom: 0;
            left: 0;
            right: 0;
        }
 
        .modal-content {
            /*overflow-y: scroll; */
            position: absolute;
            top: 0;
            bottom: 0;
            width: 100%;
        }
 
        .modal-body {
            overflow-y: scroll;
            position: absolute;
            top: 55px;
            bottom: 65px;
            width: 100%;
        }
 
        .modal-header .close {margin-right: 15px;}
 
        .modal-footer {
            position: absolute;
            width: 100%;
            bottom: 0;
        }