Find this in your style.css:
/* =Structure
----------------------------------------------- */
body {
padding: 0 2em;
}
#page {
margin: 2em auto;
max-width: 1000px;
}
Change the #page to:
#page {
margin: 1.5em auto;
max-width: 1050px;
border-top: 15px solid #bbb;
-webkit-border-radius: 15px;
-moz-border-radius: 15px;
-o-border-radius: 15px;
border-radius: 15px;
}
Add this to your functions.php:
//CUSTOM HEADER SIZE
add_filter( 'twentyeleven_header_image_height', 'voodoo_header_height');
function voodoo_header_height($param) {
return 175;
}
add_filter( 'twentyeleven_header_image_width', 'voodoo_header_width');
function voodoo_header_width($param) {
return 1050;
}
You will now have to upload a header that is 1050 x 175 px.