Design two side-by-side divs in CSS

Left div contains video or image, right div contains questions in quiz.
Left div, I used "width:60%;" and "float:left";
Right div, I use "width:35%;" and "float:right";
So the distance between two divs is 5%,
Final code:
<div style="display:block; width:60%;  overflow:auto;float: left;" > </div>
<div style="display:block; width:35%; height: 800px; overflow:auto; float: right;" ></div>