twoColumn.html

<style>
    body {
        background-color: #f3f3f3
    }
    
    .container {
        margin: 0 auto;
        width: 1280px;
        /* Or for an elastic content column. width:100%; max-width:1280px;*/
        padding: 0;
        box-sizing: border-box;
    }
    
    .banner {
        height: 150px;
        /*Dummy height for demo*/
    }
    
    .banner,
    .sidebar,
    .content {
        border: solid 1px #d1d7d9;
        box-shadow: 0px 0.5px 2px 0px rgba(0, 0, 0, 0.2);
        background-color: #FFF;
        padding: 5px;
        margin-bottom: 20px;
    }
    
    .sidebar,
    .content {}
    
    .sidebar {
        float: right;
        width: 300px;
    }
    
    .content {
        margin-right: 330px;
        /*sidebar width (300px) + box margin (20px) + content padding (2x5px)*/
    }
</style>
<div class='container'>
    <div class='banner'>banner</div>
    <div class='sidebar'>Sidebar</div>
    <div class='content'>Content</div>
</div>
<div class='container'>
    <div class='sidebar'>Sidebar</div>
    <div class='content'>Content</div>
</div>