What version of Zen Cart? v1.3.9

Is it a new install or an upgrade? New

What the addons/contributions you have installed?
* CEON URI
* Auto Twitter (Didn't work)
* Categories Dressing
* Additional Sidebox


What customizations have you made?
* Too many to count

Site is hosted using:
HostingDuo.com

Site: http://www.akihabaracosplay.com


Hello there!
I was Zenning along trying to learn CSS when I ran into some alignment issues with my header and footer. On my screen, everything looks aligned, but several of my beta testers have informed me that it's not so for their screen resolutions.

* I entered some new HTML into tpl_header.php and everything seemed good so far. Adjusted the left alignment and centered it, but to no avail, it seems.
* It looks like my custom header is overlapping the navigation bar where customers can go "Home" or "Login." I want to add these to my custom header, but am afraid I won't get the links to work properly.
* There is the usual nasty white space over the category tabs menu. I turned it off and I went into stylesheet.css to try and neg out that white space, but I can't seem to find the selector where I could do that.

Any help is greatly appreciated!

Love,
~Indi