How do I shrink the margin, expand text area?

I'd really like to expand the viewing area for text, meaning shrink the sidebar or margin area. I removed the sidebar in the "Edit Story Stylesheet" section, but the margin seemed to stay the same width, at least to my eye. On my phone it looks like too much wasted space in both the right and left margins, i.e, the text area could be wider. I know it's default but I'd like to change it. Thanks.

Twine v. 2.0.11
Harlow v. 1.2.2