Hocam her 4 dive height:50%;width:50%; verip denediniz mi ?

Örnek;

<html>
<head>
</head>
<body>

<div style="background-color:red; width:50%; height:50%; float:left">
</div>

<div style="background-color:blue; width:50%; height:50%; float:right">
</div>

<div style="background-color:green; width:50%; height:50%; float:left">
</div>

<div style="background-color:orange; width:50%; height:50%; float:right">
</div>

</body>
</html>

Ayrıca bunları da unutmayın;

html,body {
        padding:0;
        margin:0;
        height:100%;
        min-height:100%;
      }