@chchen Menlo is a very nice monospace font. In fact, recently I came to realize that I find monospace font much easier to read because the letters are relatively widely spaced. So, because I emulate the WYSIWYG feature with various CSS bits and pieces, I am using monospace font in bothe Edit and Preview modes.
My favourites are Monaco and Space Mono. Furthermore, I like dark modes, so in my browser I use the Dark Reader extension, which also allows me to set the font for webpages. The font I use there: Monaco.
Sorry for my off-topic rant, I just thought it might be useful to share.