It's not a big deal, but I wanted to make sure that I have the correct files, etc. My site logs are reporting a missing site.css file who's path should be /amember/templates/css/site.css and I looked and found that it is being referenced by the default /amember/templates/header.html file.
In addition to modifying template files, site.css is where you should be making custom changes to your site's style changes to ensure they are retained during an upgrade. This is discussed briefly in the "First Steps" section of the aMember manual: http://manual.amember.com/First_Steps and then further in the Templates Customization section http://manual.amember.com/Templates_Customization
Site.css doesn't exist though. I just dl'd the most current version of Amember and there is no site.css.