Is there a way to remove the white padding on the left and right? On mobile, it does not appear at all and the site looks cleaner. But on desktop , I get what looks like blank side navs. Here is the homepage: www.holdthatmayo.com .

Thanks for any input

Sure. Go to aATO->Style & configure LAYOUT and record what you have in the
- Layout WIDTH and type (FLUID or FIXED)
- Layout MIN width
- Layout MAX width
options.

Next set the 'Layout WIDTH and type (FLUID or FIXED)' option to 100% and set the 'Layout MIN width' and 'Layout MAX width' to spaces.

Your site will now expand t fill the viewing window no mater how wide/small a user sets it. Note: on a large monitor it might not look so good...

By the way, you should get rid of the two test menu items....

Thank you so much for the guidance! One moee quick question. Suppose I want to keep that white space but see how it looks in another color. Is that possible. I just feel like those white margins, combined with the white backround in the body, sort of washes everything out.

sure, set the page background color something ATO->Body, Text & Links->Body Style