I found the problem on your site from the custom.css file, you have fixed the width on menu site 740px. You can see it in red below:
Open templates/ja_obelisk_grayish_copy/css/custom.css file:
.container, .navbar-static-top .container, .navbar-fixed-top .container, .navbar-fixed-bottom .container {
width: 640px !important;
}
.t3-mainbody {
max-width: 740px !important;
}
.row-fluid .span12,
.span12 {
max-width: 700px !important;
}
/* end joomlart cod */
.t3-mainbody {
padding-bottom: 40px;
padding-top: 20px;
width: 740px !important;
margin: 10px 0 10px 10px;
}
.t3-mainbody .container{
width: 740px !important;
}