Re: Comments on CSS, Level 1, 23-Nov-95

Hakon Lie (
Tue, 5 Dec 1995 14:53:09 +0100 proposes:

> ========================
> bg-blend-direction
> Value: N | NW | W | SW | S | SE | E | NE
> Initial: S
> Example: bg-blend-direction: NW
> This property is used to blend two background colors. It specifies the
> direction where 'bg2' is the background color at the edge or corner of
> the window (UA display area). bg1 is the background color at the
> opposite edge or corner.
> The values are shorthands for north, north-west, west etc where N is the
> top of the window (UA display area). These directions are absolute and
> do not depend on the primary writing direction.
> The initial value is S, so if bg1 is dark blue and bg2 is light blue,
> the window (UA display area) will be dark blue at the top, smoothly
> blending through mid blue to light blue at the bottom.
> Specifying bg-blend-direction: NW would give light blue in the top-left
> corner smoothly blending through mid blue to dark blue in the bottom
> right corner.
> If only one background color is specified, the blend direction is ignored.

Taking out radial blends seems reasonable. 'canvas' is a better word
than 'window', otherwise I have no objections. Thanks.

> Note: bg-style says:
> This property describes how the background image should be laid out. By
> default, the background image is repeated in both x and y direction, and
> the image is scrolled along with the other content. A 'fixed'
> background is fixed with regard to the canvas.
> Does this apply to background color as well? If not, what is the
> behaviour if the UA cannot display all the document at once? Does it
> a) blend the colors over the whole document and then display a part of
> that blend, or
> b) blend the colors over the current window and then scroll the content
> over that fixed background?

A good point. While the latest draft introduced the pseudo-element
'$CANVAS' to address the canvas, we're about to drop it (it
complicates the syntax, and specifying background in the BODY element
is a de facto by now). Instead, the 'flow' property will see a new

Value: block | inline | canvas
Example: BODY { flow: canvas }

Thereafter, properties assigned to the BODY element will apply to the
canvas, not to the full length of the document. If a gradient over the
full length is what is wanted, one can either change the flow property
of the BODY element or address the HTML element. In that case, it's
undefined how the UA should display partial documents
(w.r.t. properties that depend on knowing the document height).

Is this reasonable?


Hakon W Lie, W3C/INRIA, Sophia-Antipolis, France