The Twine® Grimoire, Vol. 1 by Grim Baccaris
Extensive guide on using CSS with Twine, aimed at beginner to intermediate Twine users
Html2Scorm- LearningCart
Free tool for converting any folder of HTML content into a SCORM 1.2 package
CSS Button Generator: Create HTML and CSS Button Styles
Create CSS buttons
HTML 5: The Markup Language
List of elements in HTML 5, clearly indicated what's new & what elements have changed.