Theme development

I am working at a modified version of the Marvin theme. I am now interested in changing the background color of block titles, but I cannot find how. Could anybody help please?

I’m writing a new template and wonder if I should base it on chameleon or xtemplate?

So in general, what are the pros and cons between these two template systems?

FYI: The only thing the site needs special are taxonomy icons and maybe a gallery.  And myself I am a very capable programmer and only so-so designer.

I love the ADC theme, but with IE6 it seems to display the first node on a multi-node listing page incorrectly, with the left side open and the bottom not closing until the columns on either side were done (hard to explain the effect).

in any case, the fix was a simple change to the CSS file:

1) Open adc.css in a text editor

2) Find ".nodeLinks { font-size: 80%; clear: both; }"
(Without quotes)

3) Change it to:
".nodeLinks { font-size: 80%; /* clear: both; */}"
(Without quotes)

I'm updating our theme to the new 4.4/cvs architecture ... it's a mish mash of print and echo statements together with raw HTML.

Converting the functions to only return makes sense .. except one of the things our current header function is doing is calling the php header() to output raw HTTP headers, something like

I'm developing a new theme for Drupal called Pushbutton.

It's a 'hybrid' design, which means it's standards compliant (XHTML 1.0 Transitional), is backwards compatible with older browsers, and complies with accessibility guidelines (Section 508 and WCAG Priority 1).

I need to test this baby in as many browsers, systems, and devices as possible.

I'm new to PHP so I'm not sure how to do this. I made some nifty .gifs to represent the taxonomy terms on my website. I use Drupal CVS with Xtemplate and it seems like a couple lines of PHP could change the taxonomy link on a node to a taxonoxony link with a .gif.

I've looked at Polder which seems to have that feature but I think it's the old style of theme. I've checked out the Node_image but it doesn't want to work.

It seems like this can almost be hardcoded -- try to replace the link with a link and gif if the picture has the right name.

Any ideas how to start?