I believe you will want to change this line:
.wrapper{width:85%;min-width:970px;max-width:1500px;margin:auto auto;}
in your global.css file. Make sure you change easily revert the changes, and if that doesn't work, keep looking for more width references in your CSS files.
.wrapper{width:85%;min-width:970px;max-width:1500px;margin:auto auto;}
in your global.css file. Make sure you change easily revert the changes, and if that doesn't work, keep looking for more width references in your CSS files.