Ruby 工具 

<style>
    html {
        height: 100%;
    }
    body {
        margin: 0;
        padding: 8px;
        height: calc(100% - 16px);
    }
    h1 {
        margin-top: 0;
    }
    .container {
        height: 50%;
        display: flex;
        justify-content: space-between;
    }
    #left, .middle-wrap, #right {
        width: 30%;
        height: 100%;
    }
    .middle-wrap {
        position: relative;
    }
    #middle {
        width: 100%;
        height: 100%;
    }
    #copy {
        width: 70px;
        height: 30px;
        
        right: 0;
        bottom: 0;
        cursor: pointer;
    }
</style>

cjkRuby Demo