ISSUE-40: Should the <length> <length> offset be optional in a shadow?

box-shadow grammar

Should the <length> <length> offset be optional in a shadow?

State:

CLOSED

Product:

CSS3 Backgrounds and Borders

Raised by:

Bert Bos

Opened on:

2008-05-07

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.

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11. ISSUE-40 (box-shadow grammar): Should the <length> <length> offset be optional in a shadow? [CSS3 Backgrounds and Borders] (from sysbot+tracker@w3.org on 2008-05-07)

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