Ho anche provato ad allargare una immagine nell'header per vedere se si adattava ma non succede nulla...
nel file style.css ci sono queste impostazioni
/* Browser Reset */
a, abbr, acronym, address, applet, article, aside, audio, b, big, blockquote, body, caption, canvas, center, cite, code, dd, del, details, dfn, dialog, div, dl, dt, em, embed, fieldset, figcaption, figure, form, footer, header, hgroup, h1, h2, h3, h4, h5, h6, html, i, iframe, img, ins, kbd, label, legend, li, mark, menu, nav, object, ol, output, p, pre, q, ruby, s, samp, section, small, span, strike, strong, sub, summary, sup, tt, table, tbody, textarea, tfoot, thead, time, tr, th, td, u, ul, var, video { margin: 0; padding: 0; font-size: 100%; font-weight: inherit; font-style: inherit; text-align: inherit; background: transparent; border: 0; font-family: inherit; outline: 0; vertical-align: baseline; white-space: normal; }
body a { color: #5FABCD; text-decoration: none; }
body a:hover { text-decoration: underline }
body.contentpane { padding:10px;}
h1 a, h2 a, h3 a, h4 a, h5 a, h6 a { color: #000 }
h1 a:hover, h2 a:hover, h3 a:hover, h4 a:hover { color: #E95846 }
article, aside, details, figcaption, figure, footer, header, hgroup, menu, nav, section { display: block }
ol, ul { margin:0 0 0 20px }
ul.unstyled { list-style: none; margin:0; padding:0;}
blockquote, q { quotes: none }
:focus { outline: 0 }
table { border-collapse: collapse; border-spacing: 0; }
img { height:auto; max-width:100%;}
/* Grid */
.container { max-width: 1000px; min-width: 220px; margin: 0 auto; -moz-box-sizing: content-box; -webkit-box-sizing: content-box; box-sizing: content-box; }
.container .row, .col { -moz-box-sizing: border-box; -webkit-box-sizing: border-box; box-sizing: border-box; }
.row { margin-bottom: 1.5em }
.col { display: block; float: left; width: 100%; }
.col:first-child { margin-left: 0 }
.row:after, .col:after, .clr:after, .group:after { display: block; height: 0; clear: both; content: ""; visibility: hidden; }
@media (min-width:768px) {
/* grid */
.col { margin-left: 2% }
.span_1 { width: 6.5% }
.span_2 { width: 15.0% }
.span_3 { width: 23.5% }
.span_4 { width: 32.0% }
.span_5 { width: 40.5% }
.span_6 { width: 49.0% }
.span_7 { width: 57.5% }
.span_8 { width: 66.0% }
.span_9 { width: 74.5% }
.span_10 { width: 83.0% }
.span_11 { width: 91.5% }
.span_12 { width: 100% }
}