I couldn't give a damn about supporting unfinalised
standards the ACID3 tests
MS too sometimes speaks of Acid3 in dismissive terms as having little relevancy. Let's see and then decide by yourself, is this stuff important: DOM2 Core
DOM2 Events
DOM2 HTML
DOM2 Range
DOM2 Style (getComputedStyle, …)
DOM2 Traversal (NodeIterator, TreeWalker)
DOM2 Views (defaultView)
ECMAScript
HTML4 (<object>, <iframe>, …)
HTTP (Content-Type, 404, …)
Media Queries
Selectors (:lang, :nth-child(), combinators, dynamic
changes, …)
XHTML 1.0
CSS2 (@font-face)
CSS2.1 (‘inline-block’, ‘pre-wrap’, parsing…)
CSS3 Color (rgba(), hsla(), …)
CSS3 UI (‘cursor’)
data: URIs
SVG (SVG Animation, SVG Fonts, …)
(Taken from: http://www.webstandards.org/action/acid3/)Looks important to me.