Does Your Browser Work?

The World Wide Web and the HTML markup language have evolved, which has presented a challenge for people writing Web browser software.

Some Web sites offer a label that says, “optimized for Internet Explorer” or “optimized for Netscape Navigator”. Generally, what this label really means is that the Web site is not standards-compliant and may not work properly in other browsers.

Unfortunately, what browsers can and can't handle also varies from version to version. For example, a Web page that displays properly in IE version 5.5 may not display properly in IE version 6. My choice of that example is not random; it comes from experience with one of my own Web sites.

The good news is that standards do exist, there are browser choices, and there's a way to check if your browser correctly displays valid Web pages. The browser test is quick and easy and will give you a lot more confidence that the Web page itself is wrong, not you.

A test based on standards is available at http:/ / To run the test, all you have to do is go to the Web page and click on Take the Acid2 test. On the page you will see two links:

  • Take the Acid2 Test
  • The Reference Rendering

You should see the same thing when clicking on each link. The figure below shows what the result should look like.

The difference is that when you take the test, the Web page uses features of HTML, CSS (Cascading Style Sheets) and PNG (portable network graphic) to show the Web page. Your browser then must create the page using this encoded information. When you click on the reference rendering link, it is simply a file containing the image.

The following figure shows how the Firefox browser on my SUSE Linux system displayed the test. On this same system, older versions of Konqueror and Opera also displayed the test incorrectly. On my Kubuntu system, Konqueror and Opera 9 displayed the test correctly.

Phil Hughes is Publisher for Tux Media, Ltd.

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fyl - Wed, 2021-01-10 20:17.

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Not Ironclad

The Acid2 test may be a useful guide, but don't take it as law. Just because a browser passes it doesn't mean that browser is actually standards-compliant, and just because a browser fails doesn't mean it's broken.

Konqueror, for example, passes Acid2 in spite of handling "position: absolute" incorrectly. According to the standard:

"The containing block for a positioned box is established by the nearest positioned ancestor..."

"Positioned ancestor" means any element with a "position" property other than "static" or a "float" property other than "none". Konqueror, however, only considers elements with "position: relative" as establishing a containing block for positioned elements. As a result, nesting two absolutely positioned element one inside the other does not work correctly in Konqueror -- both are positioned relative to the viewport, when the inner should be positioned relative to the outer.

Firefox, on the other hand, handles positioned elements just like the standard says it should.

As it happens, I've actually had Konqueror barf on standards-compliant pages more often than Firefox. So maybe passing Acid2 isn't really all that important after all.

Ryukage (not verified) - Sat, 2021-01-13 07:04.

OK, now what?

Well, FF failed on my Ubuntu machine...this article would be great if it gave some sort of advice...

Brand - (not verified) - Thu, 2021-01-11 12:18.


This desktop is running Kubuntu Dapper Drake with all the latest updates. I was surprised but your observation appears to still be the case: FireFox fails.

I tried Opera version 9.10 and it works perfectly. I am not positive but I believe I downloaded this from the Opera site, but I do know that opera is included in the Dapper repositories if you enable universe and multiverse.

I then tried the test in the current version of Konqueror and it works perfectly. So, it appears FireFox is the only bad guy right now.

PS: Thanks for the link correction.

fyl - Fri, 2021-01-12 06:25.


The syntax for the link you provided for the test needs fixed, has double "http://"'s.

Brand - (not verified) - Thu, 2021-01-11 12:22.