html,
body {
    margin: 0;
    padding: 0;
    height: 100%;
    width: 100%;
    /* it wil show no scrollbar dont worry it will show only when there is more content */
    overflow: hidden;
}

#editor {
    height: 100%;
    width: 50%;
    display: inline-block;
    /* now here you can control all the editor styling */
    line-height: 35px;
    font-family: 'Consolas';
}

#container {
    height: 100%;
    /* width auto means that it will adjust the width according to the height :) */
    width: auto;
    white-space: nowrap;
    overflow: hidden;
    /* Postion relative  */
    position: relative;
}

#iframe {
    height: 100%;
    display: inline-block;
    width: 50%;
    /* i put spacing there because the user will do the styling with out editor  */
}