To what extent should a website accommodate minority browsers -- that is, for practical purposes, anything other than Netscape and MS Internet Explorer versions 3 and higher? The issue arises because each new generation of browser adds functions not implemented by earlier versions. (Here's some background on the web and browsers.)
The most conservative approach would be to design the site using only the most basic components of html, so that all browsers everywhere would display the site without problems. Almost no one does this anymore. Sites that do are what David Siegel, the "killer web sites" guy (see www.killersites.com) calls first-generation sites -- they have default (usually gray) backgrounds, plain text that spreads across the browser window, no graphics. (I disagree with about half of what Siegel advocates; perhaps I'll write about that some other time.) Such site design can be eminently suitable in some cases, especially those entirely content-driven: for example, Locus's own books database.
At the opposite extreme are those professional sites (i.e., those with a workforce of designers and editors behind them, who get paid) which employ all the latest browser facilities -- frames, Java or Active-X code that implements ticker-tape messages or drop-down menus, etc. -- and high-quality graphics. These sites are gorgeous, but they are high-maintenance, and they unavoidably lock out a segment of the browsing audience, those with older browsers that cannot display such advanced features -- or who can but whose slow connections cause frustration downloading the huge graphics files involved. (Maintaining alternate pages for the browser-challenged is also high-maintenance.)
This website leans more toward the conservative than the advanced, both because there is no professional staff available to maintain a complex site, and so that as few browsers as possible are excluded from viewing. This new Locus Online site does use one or two tricks that the old site didn't -- that is, it relies on features of Netscape/IE 3.0+ that are not implemented in earlier versions. See the disclaimer off the cover page for further details.
A related concern applies to hardware. Many users have relatively small monitors (14 inch) set to low resolutions (800 by 600, or even 480 by 640) and that display only 256 colors. Even simple graphics programs (like Paint Shop Pro, which is mostly what I've used for this site) allow simple creation of graphics with millions of colors. But there's no point in using them if most browsers won't see them. Worse, the browsers with limited palettes (256 colors instead of thousands or millions) will necessarily shift the intermediate colors it gets to those it can display. This sometimes produces an unpleasant 'dithering' effect -- a stippled effect in an area of solid color.
The solution for this is one that most websites, even the fancy professional ones, do apply to an extent: they confine their palettes (the range of colors used) to a standard 256, at least for graphics that involve solid areas of color (as opposed to scans of photos, book covers, etc.). This avoids obvious dithering effects. The colors of the page banners on this site, and the shading of the sidebar submenus, are chosen from the standard 256 palette.
Another widely applied design guideline driven by hardware limitations is the width of a standard webpage: 600 pixels, more or less. This means that even if you have your browser displayed full screen, on a big monitor set to high resolution, you won't see any page of this site -- or of the vast majority of professional sites -- wider than the fixed width of 600 pixels.