Increase the width of the sidebar

Hello all,

I would like to increase the width of the sidebar on my site and decrease the width of my main content. (In effect keeping the total width the same.

My website is https://www.shewearswhite.com

I would like for my main content to be approx 650 pixels wide, currently it is 740. I can adjust this part but when I do the sidebar remains the same.
I’m not sure how wide my sidebar is, I believe it to be around 220 pixels, I would like to increase it so my search function shows on one line, currently the the search button defaults to below the search function.

I purchased the Elle theme through studiopress and it seems I can only change the css in the stylesheet.css, below I have included the code that I believe relates to the width of the main content and the sidebar.

Any help would be be hugely appreciated!! Thank you.

[CSS moderated. You only need to post a link to your site.]