Take a look in your responsive section and adjust the width from there –
/*
24 Media Queries
---------------------------------------------------------------------------------------------------- */
/* Desktops, laptops and iPads (landscape) ----------- */
@media only screen and (max-width: 1200px) {
#header,
#nav .wrap,
#subnav .wrap,
.slider-inner,
#welcome .wrap,
#home-feature-bg .wrap,
#home-feature-bg-alt .wrap,
#home-feature-bg-dark .wrap,
#inner .wrap,
.footer-widgets .wrap,
#footer .wrap {
width: 960px;
}
}
Try increasing the – 1200px width and then decreasing the 960px width to 600px until you get the result you want.