Another pure css based solution that is based on two clipped rounded elements that i rotate to get to the right angle:
http://jsfiddle.net/maayan/byT76/
That's the basic css that enables it:
.clip1 {
position:absolute;
top:0;left:0;
width:200px;
height:200px;
clip:rect(0px,200px,200px,100px);
}
.slice1 {
position:absolute;
width:200px;
height:200px;
clip:rect(0px,100px,200px,0px);
-moz-border-radius:100px;
-webkit-border-radius:100px;
border-radius:100px;
background-color:#f7e5e1;
border-color:#f7e5e1;
-moz-transform:rotate(0);
-webkit-transform:rotate(0);
-o-transform:rotate(0);
transform:rotate(0);
}
.clip2
{
position:absolute;
top:0;left:0;
width:200px;
height:200px;
clip:rect(0,100px,200px,0px);
}
.slice2
{
position:absolute;
width:200px;
height:200px;
clip:rect(0px,200px,200px,100px);
-moz-border-radius:100px;
-webkit-border-radius:100px;
border-radius:100px;
background-color:#f7e5e1;
border-color:#f7e5e1;
-moz-transform:rotate(0);
-webkit-transform:rotate(0);
-o-transform:rotate(0);
transform:rotate(0);
}
and the js rotates it as required.
quite easy to understand..
Hope it helps, Maayan