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CHAPTERFormatting Your Pages 4
The Web-Safe Palette
In the early days of the Web, most monitors were
capable of displaying only 256 colors, of which only
216 were shared between Windows and Macintosh
systems. Thus, the Web-safe palette, representing
those 216 colors, was developed. Today, there is no
reason to limit yourself to this palette because all
modern monitors can handle millions of colors.
Accessibility and Colors
Current estimates are that about 5% of the population is to
some degree color blind. Color blindness normally manifests
itself as an inability to distinguish contrasts between similar
colors. When you are picking your site’s color palette, keep
this issue in mind and be sure to select colors with sufficient
contrast. This is particularly important when picking your
text and background colors. Web sites such as http://www.vischeck.
com/vischeck/vischeckURL.php can be helpful in checking
your site’s colors.
Poor Contrast Good Contrast
CSS 3 and Alpha
Version 3 of the CSS specification will add the ability to
specify an alpha channel, or transparency, to colors. You
can use the RGBA syntax: rgba(128,0,128,.5), which
creates a purple with 50 percent transparency. Browser
support for CSS3 is still very sporadic, so you should
carefully test this to ensure that it works in your target
browser set.
RGB (128,0,128)
RGBA (128,0,128,.5)