But, the terrible truth out there is that not everyone has your computer. . .

. . . or your browser. Or your monitor.

And, the truth be told, your page could appear just plain terrible to everyone else.

To avoid this, you need to test your page. Rigorously.
Here are some problems to watch out for:

Cross-browser Mix-ups
Remember, there are still two main browsers out there, with four different versions. A page that looks great in Netscape 4.0 may look terrible in MSIE 1.0. And a lot of people still use 1.0. Just ask your local ISP. Millions of people are out there who got 1.0 bundled with their version of Windows95. They don't know any better. They just think your page looks terrible. For the love of corn, MSIE 1.0 doesn't even support transparent gifs! Yahoo doesn't even look good!

Of course, there are ways around this. All my pages are backwards compatible all the way back to Netscape 2.0. Does that mean I'm ignoring earlier versions? No. I simply design the page in a way that it can be viewed well by any browser, or provide a text-only version.
It used to be that almost every good page out there had a text-only version. Now, it's a struggle to find one. Sure, nobody uses lynx anymore, but there still are a lot of 386/14.4 users out there that simply don't want to wait. The nicest thing you can do to them is to put ALT, HEIGHT, and WIDTH tags in all of your images. That way, your page looks good even if they have their images turned off. Yes, some people still do that.

Another problem is that browsers differ when going across platforms. Macs do make up a quarter of the internet population, but to see some pages you wouldn't think it. If you can make downloadable files cross-platform, do it. It may be hard for some, but it's even harder to assume a Mac user has a copy of MacZip. Of course, it goes both ways. Mac users compromise even more of the serious page designers (a *gasp* majority!), and they can screw up, too. One such example is graphic quality. Many Mac browsers do not limit themselves to a 216-color palette like PC versions of Netscape. Therefore, graphics viewed in a Mac browser and then in a PC version may be victims of terrible dithering if not put through some sort of color reduction.

Also, Mac browsers sometimes align things differently in frames. An example: If you have a single table inside a frame, some Mac versions of Netscape will appear to forego the line break that comes automatically with a table. In other words, it will put any text in the table at the top of the frame, instead of putting a line break in first. But, when you come back to the page or reload it, it does put the line break in, like in a PC browser. Confused yet? My point is, that in certain situations like that, a Mac frame may show all the text with a height of 40, while for PC browsers, it needs to be set at 70 or more.

Screen Sizes
Beyond platform and browser problems, there lies the even more common mistake of screen sizes. Not everyone has a 640x480 screen, but a quite a few people do. That means that what looks great on your 17-inch monitor might just be a pain to read on Bob's little 14-inch. And vice versa. If you want your backgrounds to flow with the page, make sure they still flow when the screen is bigger. Or smaller. Netscape 2.0, for some inexplicable reason, makes Macs' page screen sizes smaller than the screen. Why? No one knows. At least not me. But Netscape 2.0 is still a well-used browser, so you have to prepare for screens smaller than yours. Or bigger. A lot of people have 800x600 or larger displays. Find one and test your page on it.

In other words, test your page on every browser and computer you can get your hands on.

The bottom line: Make it so that your page looks good on MSIE and Netscape 2.0 and higher, and is at least usable on anything lower. It's the safe way to go, and the easy way to get everyone using your page.