I want to change the current font size for posts only.
OPTION 2 - SERVER SIDE:
Control Panel > Styles > [SELECT YOUR STYLE] > EDIT
Find the font items you want to increase the size of for everybody on your site. Increase their "font-size:" numbers from "12px;" to "14px;" or by a factor of 2 or 3. Whatever you feel comfortable with. [...] "post_inner" in Post Properties.
"post_inner" - would be for the post content.
"form-input" - would be for the box which the user types in to.
