@Will: Catch Evolution Pro theme is responsive design theme so adjusting width is little complex, as you need to adjust for various screen sizes. So, I just recommend you to change to large screens. In the following css, I have reduces the width of the third sidebar by 40px and increase the width of Right second sidebar by 40px as per your question. So, just add the following css in “Appearance => Theme Options => Custom CSS” box:
/* For Screen size above 1060px */
@media screen and (min-width: 1061px) {
.three-columns .content-sidebar-wrap { width: 794px; }
.three-columns #secondary { width: 330px; }
.three-columns #third { width: 200px; }
}
/* For Screen size above 1224px */
@media screen and (min-width: 1225px) {
.three-columns .content-sidebar-wrap { width: 960px; }
.three-columns #secondary { width: 400px; }
.three-columns #third { width: 200px; }
}