You could also use a bit of css to fix this. Target the img itself
.img { width: 100%; height: auto }
@only screen and (min-width: 1440px) #bodywrap { max-width: 100% } will make it full width. You will have to then space out the content from the side of the page
What is the theme are you using?
Could you link to the page so I can get a visual representation of what it is 🙂
.site-bar .nav { width: 85% }
.site-tools { width: 15% }
These should fix it for you
