For Discourse the font size is set at 14px on the html element. Most of the other fonts are sized using the βemβ unit. For example the heading of this topic has a size of 1.8 em. To convert an em unit to px you multiply the em unit by the size of the current font (1.8 em * 14px). If you change the font size on the html element or the body element, that change will cascade throughout the application. Itβs done that way on purpose. It does mean that if you change the base font size you might have to adjust font sizes and possibly some margins and padding in a few other places.
Maybe you can get away with changing the font size on .container.posts or .topic-body
Right, all font sizes cascade from the 14px set on the HTML tag β so you can bump everything up proportionately by doing
html {
font-size: 16px;
}
or if you just want to increase the font size of a specific section, that still works too β just find a parent container and apply a font size there. For example, posts: