Update mmenu.css

- make use of hardware accelaration in line 58. In this way, mobile version of webkits as well as firefox will have smooth animation. rather than to use the left property.
 - made left:0 and margin: 0 in line 76 for the hardware acceleration
 - changed padding to 0 in line 139
 - changed lin 624 to 
@media all and (min-width: 500px) {

	.mm-menu
	{
		width: 500px;
	}
	
}

NOTE: this is to make use of Css3 translate3d so that it will be smoother to animate.