This is my code for CSS Column
<div id="a">
    <div class="b"></div>
    <div class="b" style="height:30px;"></div>
    <div class="b" style="height:30px;"></div>
    <div class="b"></div>
    <div class="b"></div>
    <div class="b"></div>
</div>
<style>
    #a {
        position: relative;
        display: block;
        background:yellow;
        width:500px;
    }
    .b {
        background:pink;
        width: 40%;
        display: inline-block;
        height:50px;
        vertical-align: top;
        margin:10px;
    }
</style>

 
     
     
    