I’m not quite sure what you mean. There is a default font size for both the archive and the forum, but every member has the option of adjusting that size for themselves via the Rich Text Editor in the archive or here in the forum. The default here is Arial 14 and that is what I’m seeing your post above as using. The default font in the archive, as I see it on my desktop (22” monitor) and laptop (14” display), without zooming, is the same size. I never access the site on a tablet or smartphone, because I prefer a larger screen for viewing, to be quite honest. We did, however, rework the archive code to accommodate mobile device users, eliminating most of the left column menus and other features which were not mobile-friendly (although this desktop user quite liked them).
If a story’s text is spilling over the page borders, that is another issue altogether, and has to do with repeating characters used within the story text, and how the site draws those characters. People use them as scene breaks, or dividers, and it glitches the way the story displays on the screen. In that case, the author needs to remove the repeating characters, since that’s something we moderators can’t fix for them.
You do have the option on most computers of setting your computer’s default display for text to a larger font. That might help, if that’s the method you use to view the site. Other than that, without knowing how you access the site or what OS you use, I can’t offer any other helpful advice.