Aw, , :) , , jQuery.

: $('li').semiCircle(300,50,200,100);β
:
jQuery.fn.semiCircle = function(cx,cy,radius,radiusY,startDegrees,endDegrees){
if (radiusY===undefined) radiusY = radius;
if (startDegrees===undefined) startDegrees = 0;
if (endDegrees===undefined) endDegrees = 180;
var startRadians = startDegrees*Math.PI/180,
endRadians = endDegrees*Math.PI/180,
stepRadians = (endRadians-startRadians)/(this.length-1);
return this.each(function(i){
var a = i*stepRadians+startRadians,
x = Math.cos(a)*radius + cx,
y = Math.sin(a)*radiusY + cy;
$(this).css({position:'absolute', left:x+'px', top:y+'px'});
});
};