try this css:
/* Show in default resolution screen*/
#container2 {
width: 960px;
position: relative;
margin:0 auto;
line-height: 1.4em;
}
/* If in mobile screen with maximum width 479px. The iPhone screen resolution is 320x480 px (except iPhone4, 640x960) */
@media only screen and (max-width: 479px){
#container2 { width: 90%; }
}
Here the demo: http://jsfiddle.net/ongisnade/CG9WN/