css/layout.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
<section class="float">
    <style>
        .float .left {
            float: left;
            width: 300px;
            height: 200px;
            background: green;
        }
        .float .center {
            background: yellow;
            height: 200px;
        }

        .float .right {
            height: 200px;
            width: 300px;
            float: right;
            background: red;
        }
    </style>
    <article class="left-center-right">
        <div class="left"></div>
        <div class="right"></div>
        <div class="center"></div>
    </article>
</section>
</body>
</html>