How do enlarge the font on the default theme? I've tried google and old posts reference a CSS Style Sheet that apparently doesn't exist anymore. 

You can add this to your custom.css file

	/* Makes post body font larger (default is 14px) */
 .ipsType_normal {
font-size: 16px;
}
	

When I use that CSS it also styles my H2 titles on the front page. Is there  a way to use CSS :not()  to style the fonts that aren't H2?

OK, I think I may have achieved what I want with this CSS. Only the body of articles and the body of forum topics is effected. 

 

.ipsType_normal.ipsType_richText {
    font-size: 18px;
}