=====style=======
body    {margin:0}
.slider  {margin-top:0;
         margin-bottom:0;
         width:50%;
         height:50%;
         float:left;
         background-color:#ff99ff}
.main    {margin-top:0;
         margin-bottom:0;
         width:50%;
         height:50%;
         float:right;
         background-color:#ff9933}
.footer  {margin-top:0;
         width:100%;
         height:50%;
         background-color:#ffff00}
.float	{position:absolute;
        width:30%;
	    height:30%;
	    top:30%;
	    left:30%;
	    background-color:#ffffff;
	    z-index:1}

=====body=======
<div class="slider">slider</div>
<div class="main">main</div>
<div class="footer">footer</div>
<div class="float">float</div>


<!-- test.file@06.11.16.by_tajima -->