Elements involved in transition from basic to advanced:

coding - how to clean up code so that things work
design sense - judgement and humility to know if things don't look right
colors - 216 color palette - page colors, background graphics, text and link colors
thorough knowledge of basic linear text and graphics layout
graphics applications
tables for page layout
semantic and navigation design
graphic design skills - alignment, typography, color
usability
user engagement
forms and processing
essential Javascript - mouseovers, menus, pop-up windows
Toybox knowledge:
What's out there in JS
HTML 4 enhancements and degradations - Margins, stylesheets, layers
Streaming media
Shockwave and Flash
server enhancements - FrontPage extensions, available scripts, available database enhancements