This results when transparency was created for a light background, and the graphic is used against a dark background. Pixels that are nearly white are not made transparent, so produce the halo. Some individual pages do not fit left to right on an 800 X 600 screen. This can distort the image if you don't maintain the original ratio of height to width. Also, the graphic will look small, but will actually still be large, and so may take a long time to download.
Some pages have lots of animated graphics.
These appear to load quickly enough when loading is from your local drive, but may take too long over a dial-up line. The instructor edited links at the bottom of the individual theme pages to reflect the directory structure of the site. The instructor converted all bmp graphics files to jpg. Although IE will recognize it, other browsers, including Netscape, will not. Themes shown in blue correspond to pages that contained copywrited images.