After the Acid3 test page is completely rendered, the word Acid3 can be clicked to see an alert (or shift-click for a new window) explaining exactly which subtests have failed and what the error message was.
In case one of the 100 tests passed but took too much time, the report includes timing results for that single test.
The alert reports the total time of the whole Acid3 test.

In order to render the test correctly, user agents need to implement the CSS 3 Text Shadows and the CSS 2.x Downloadable Fonts specifications, which are currently under consideration by W3C to be standardized.
This is required as the test uses a custom TrueType font, called "AcidAhemTest", to cover up a 20x20 red square.
Supporting Truetype fonts however is not required by the CSS specification.
A browser supporting only OpenType fonts with CFF outlines or Embedded OpenType fonts could support the CSS standard, but fail the test in the Acid3 test.
The glyph, when rendered by the downloaded font, is just a square, made white with CSS, and thus invisible.

In addition, the test also uses Base64 encoded images, some more advanced selectors, CSS 3 color values (HSLA) as well as bogus selectors and values that should be ignored.
After the Acid3 test page is completely rendered, the word Acid3 can be clicked to see an alert (or shift-click for a new window) explaining exactly which subtests have failed and what the error message was. In case one of the 100 tests passed but took too much time, the report includes timing results for that single test. The alert reports the total time of the whole Acid3 test.
In order to render the test correctly, user agents need to implement the CSS 3 Text Shadows and the CSS 2.x Downloadable Fonts specifications, which are currently under consideration by W3C to be standardized. This is required as the test uses a custom TrueType font, called "AcidAhemTest", to cover up a 20x20 red square. Supporting Truetype fonts however is not required by the CSS specification. A browser supporting only OpenType fonts with CFF outlines or Embedded OpenType fonts could support the CSS standard, but fail the test in the Acid3 test. The glyph, when rendered by the downloaded font, is just a square, made white with CSS, and thus invisible.
In addition, the test also uses Base64 encoded images, some more advanced selectors, CSS 3 color values (HSLA) as well as bogus selectors and values that should be ignored.
Acid3