Theme development

I'm encountering an interesting bug in IE6 on my web site, where the background colour for the first block / node on a page doesn't get implemented. If you visit my site http://dash.yi.org and look at the files page for example, you will see what I mean.

I'm using the ADC theme, but I'm lost as to what I can change to fix this. Obviously, the true answer is to use Mozilla, where it renders perfectly. But I'm a perfectionist ;) any ideas?

After discarding the interlaced theme because of lack of support for adding header links and my own limited knowledge, i'm in the task of making my own template this time using the xtemplate.

After making several changes in the css i see that all my changes related to text and graphics work as intended but the backgrounds are not showing in Mozilla 0.9.1 or IE 6.0.28.
The strange part is that if i use the WebDeveloper Plug-in of Firefox and click the Edit CSS then the backgrounds appear. ?:(

There exists a php drupal function to know which user is visiting a page?

thanks

I see that the Theme Tutorial has been removed from the Drupal handbook. I have quite a bit of HTML experience, but not much with CSS or PHP.

I am wanting to learn and would like to know where some good general references might be and some specific Drupal references.

The first project I'm working on is taking some of the graphics elements from:
http://www.impactaction.org
and converting them to Drupal.

Any thoughts?

I'll post here as well hoping to find a solution...

I'm trying to figure out, with no success, how to display entries without
repeating each time the date. I want to format the page so that it shows the
date, then all the entries for that day.

By default drupal just repeats the full date with each post, I just want to
group them day by day. I've seen it's possible since it works here:
http://integrationresearch.org/aggregator

I'm starting to get crazy. I've switched to this theme hoping to be able to customize it more easily but I cannot make it work right. For some strange reason the modified main.tpl.php works only for registered and logged users. Why?

How can I make the site look the same for both anonymous and registered users?

Only that theme and style is enabled but it still behaves differently for anonymous users.