<!DOCTYPE html> 
<html> 
<head> 
</head> 
<body>
    <style>
        #test {
            position: absolute;
            width: 100px;
            height: 400px;
            background: rgba(255, 0, 0, 1);
        }
        #test2 {
            position: relative;
            left: 100px;
            width: 100px;
            height: 400px;
            background: rgba(255, 0, 0, 0.5);
        }
    </style>
    </div id="container">
        <div id="test"></div>
        <div id="test2"></div>
    </div>
</body> 
</html> 
