Div width for relative position

Question

My code:
<div id="box">I am a box</div>
#box{
width:100px;
height:100px;
background:red;
position:relative;}

As you see,Ive setted my div width and height into 100px but it doesnt seen to work.It keeps defining its width and height as the width and height of the element inside because of the relative position.
Can anyone tell me is there anyway to set the div position into "relative" while setting its width and height to 100px?