SOURCE

    <div class="box">

        <iframe id="frame" 
            src="https://www.baidu.com" 
            frameborder="0" 
            style="position:absolute; top:-50px; width: 100%; height: 100%;"
        ></iframe>
       </div>

html,body {
            height: 100%;
        }
        .box {
            padding: 20px 20px;
            border: 2px solid #ccc;
            position: relative;
            height: 100%;
            overflow: hidden;
        }