Make Category Page Full Width

Friends,

I am new to WP, launched a website a few months ago, didn’t use a Child Theme and well… you know how that ended. So I started from scratch with a new theme (Ignite Theme).

I recently created a Category of posts which now appears on a page by itself but it is not full width. The CSS edit that I plugged into Jetpack to get my main Posts page to go full width was:

.blog .main, .singular-post .main {
width: 85%;
}

Wondering how to do the same thing on this new category/post page: http://www.davidssanchez.com/category/october-february/

Thanks in advance.
David