Good web application development separates the three Ss: structure, style, and scripting. See this Web Development Introduction.
Helpful Bookmarklets
The Cascading Style Sheets, level 2 (CSS2) Specification is where you'll find most of the technical information you need. I usually find the CSS2 property index the best quick reference.
Although there are a few helpful color scheme applications, they all seem to emphasize choosing hues without paying attention to necessary contrasts in saturation and value.
Also, stick with web-safe colors.
Flowcharts
Graphs
Test jpgraph format plugin: (Currently disabled.)
** "jpgraph_line" format not configured for xhtml output**
** "jpgraph_line" format not configured for xhtml output**
** "jpgraph_line" format not configured for xhtml output**