)
Because of these restrictions, GIF89s are not used all that much these days. They do cling
on in one area of web design, though: as spacers for stretching table cells, in order to lay
out a page. However, in these enlightened times, that type of technique should be
avoided, since you can lay out precisely spaced pages much more easily using CSS.
THE ESSENTIAL GUIDE TO CSS AND HTML WEB DESIGN
128
PNG
For years, PNG (pronounced ping, and short for Portable Network Graphics) lurked in the
wilderness as a capable yet unloved and unused format for web design. Designed primarily
as a replacement for GIF, the format has plenty to offer, including a far more flexible
palette than GIF and true alpha transparency. Some have mooted PNG as a JPEG replacement,
too, but this isn??™t recommended??”PNGs tend to be much larger than JPEGs for photographic
images. For imagery with sharp lines, areas of flat color, or where alpha
transparency is required, it is, however, a good choice.
The reason PNG is still less common than GIF or JPEG primarily has to do with Internet
Explorer. Prior to version 7, Microsoft??™s browser didn??™t offer support for PNG alpha transparency,
instead replacing transparent areas with white or gray. Although a proprietary
workaround exists (see Chapter 9??™s ???Dealing with Internet Explorer bugs??? section), it isn??™t
intuitive, and it requires extra code. With post??“version 6 releases of Internet Explorer
finally supporting alpha transparency (and Internet Explorer??™s share of the market decreasing
somewhat, primarily due to competition from Firefox), it??™s worth looking into PNG
when creating layouts.
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