#main {
        display: none;
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
      }
      #box {
        width: 300px;
        height: 550px;
        text-align: left;
        padding: 15px;
        border: 3px solid #0000cc;
        border-radius: 10px;
        color: #ffffff;
        background-color: #0010cc;
        position: absolute;
        top: 0;
        right: 0;
        bottom: 0;
        left: 0;
        margin: auto;
      }
#main:target {display: block;}