The TW heading syntax uses between 1 and 6 "!" to generate different levels of heading (Hn) DOM elements. You can customized the default font size for thse elements by using CSS like this:
In TiddlyWiki Classic, you can place the above CSS into the specially-named tiddler, [[StyleSheet]].
In TiddlyWiki 5, just place the desired CSS into any tiddler, and then tag it with "$:/tags/stylesheet".
enjoy,
-e
Eric Shulman
TiddlyTools / ELS Design Studios
YOUR DONATIONS ARE VERY IMPORTANT!
HELP ME TO HELP YOU - MAKE A CONTRIBUTION TO MY "TIP JAR"...
Professional TiddlyWiki Consulting Services...
Analysis, Design, and Custom Solutions: