2008-05-07 10:16:58: Created issue 'Should the <length> <length> offset be optional in a shadow?' nickname box-shadow grammar owned by Bert Bos on product CSS3 Backgrounds and Borders, description 'See also thread at http://lists.w3.org/Archives/Public/www-style/2008May/0035.html
1) [Minor:] the grammar contains two errors: it requires at least two shadows instead of one; and it makes the comma optional. The best fix depends on the answer to the next question.
2) The offset (<length> <length>) is optional and defaults to '0 0', which means that an omitted offset makes the shadow invisible and is thus almost never useful. There are at least two solutions: require an offset or make the default more useful.
The similar 'text-shadow' property (http://www.w3.org/TR/2007/WD-css3-text-20070306/#text-shadow)
makes the offset required. Whatever solution is chosen, 'box-shadow' and 'text-shadow' should probably have the same syntax.
* Solution 1, don't omit the offset:
none | <shadow> [ , <shadow> ]*
where <shadow> is
<length> <length> <length>? <color>? |
<color> <length> <length> <length>?
* Solution 2, better default offset:
An omitted offset could default to '1px 1px' or to a value chosen by the UA.' non-public [Bert Bos]