Using the web standard compliance tests at acidtests.org [1] one can check the how well different browser adhere to web standards.When running the Acid3 test the browser should render according to this reference. 

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I performed a quick check with some browsers on a Windows XP installation, just to see how well they perform. The higher the number the better, with a maximum of 100 points. Running the acid3 test the result came out like this:

1. Chrome 3.0.195.6 / Safari 4.0.2 (530.19.1) - 100 points

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   Fig. 1-1 - Chrome 3.0.195.6

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   Fig. 1-2 - Safari 4.0.2 (530.19.1) 

2. Firefox 3.5.2 - 93 points

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   Fig. 2 - Firefox 3.5.2

3. IE8 (8.00.6001.18702) - 20 points

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   Fig. 3 - IE8 (8.00.6001.18702)

4. IE8 (8.00.6001.18702; compatilibity mode on) - 13 points

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   Fig. 4 - IE8 (8.00.6001.18702; compatilibity mode on)

5. IE7 - probably just 5 points, hard to tell

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   Fig. 5 - IE7

The result speaks for itself.