body {
    padding: 10px;
    background-color: #f1f1f1;
}
main {
    background-color: #fff;
    height: 85%;
    border-radius: 5px;
    box-shadow: 0 0 3px rgba(0,0,0,.3);
    margin-bottom: 8px;
}
.main-board {
    float: left;
    width: 50%;
    height: 100%;
    overflow: auto;
}
.main-board:first-child {
    border-right: 1px solid #cad9ea;
}

/* 尾部 */
footer {
    height: 11%;
    background-color: #fff;
    border-radius: 5px;
    box-shadow: 0 0 3px rgba(0,0,0,.3);
}
#output {
    color: #666;
    border: 1px solid #b9b9b9;
    width: 100%;
    height: 100%;
    overflow: auto;
    resize:none;
}