Use the default font size by default

[koraa]

Before this, fonts inside docdash where rendered
slightly larger than the average font on other sides.

In practiced this caused some of us to try do make the
font size smaller again since this would fit less information,
especially for smaller screen sizes (mobile devices).

This reverts to using the default font size for prosaic
text; this allows users to set the optimum font size for
their eyes & needs.

[ar2rsawseen]

The design decision to use larger font was made by original author, and I would like to stay by that.
But I do get a point about it being problematic on mobile devices. So maybe this can be solved with the help of media query, rather than change font for all cases.