Radial Gradient Readability

We’ve agreed that radial gradients should have a literate syntax. Linear gradients already kinda have one, in a simple way, and hopefully radials should end up thematically consistent.

Latest Proposal

for CSS3: radial-gradient([ <extent> || <shape> ] at <position>, <colors>)
for CSS4: radial-gradient([ <extent> || <shape> ] at <position> [from <position> | from-offset <length>{1,2}], <colors>)

Because the default size is cover, this means:

radial-gradient(from 25% 25%, <colors>) makes the 0% color at 25% 25%, and the 100% color is at a box-centered box-covering ellipse.
radial-gradient(at 25% 25%, <colors>) makes the 0% color at 25% 25%, and the 100% color at a 25% 25%-centered box-covering ellipse.

Illustration of moving geometric center vs. moving color focus

(view in webkit)

The <extent> is either a farthest/closest-side/corner keyword or an explicit <length>{1,2}. Example: radial-gradient(5em circle at 10% 15%, white, black)

Everything is optional except the colors. Examples: radial-gradient(5em, white, black), radial-gradient(circle, white, black), radial-gradient(at top left, white, black), radial-gradient(white, black).

Syntax Comparison for Level 3
Current WD	Latest ED
`radial-gradient(white, black)`	`radial-gradient(white, black)`
`radial-gradient(center, farthest-corner ellipse, white, black)`	`radial-gradient(farthest-corner ellipse at center, white, black)`
`radial-gradient(top left, white, black)`	`radial-gradient(at top left, white, black)`
`radial-gradient(top left, farthest-corner ellipse, white, black)`	`radial-gradient(farthest-corner ellipse at top left, white, black)`
`radial-gradient(circle, white, black)`	`radial-gradient(circle, white, black)`
`radial-gradient(circle, center, white, black)`	`radial-gradient(circle at center, white, black)`
`radial-gradient(center, 5em 5em, white, black)`	`radial-gradient(5em, white, black)`
`radial-gradient(center, 5em 5em, white, black)`	`radial-gradient(circle 5em at center, white, black)`
`radial-gradient(75% 75%, closest-side circle, white, black)`	`radial-gradient(closet-side circle at 75% 75%, white, black)`
`radial-gradient(25% 2em, 15px 30%, white, black)`		`radial-gradient(15px 30% ellipse at 25% 2em, white, black)`

Original Proposal

The original proposal was radial-gradient(<shape> to <extent> at <position>, <colors>). In this proposal all arguments after <shape> could be reordered. However, feedback on CSS3.info indicated that people find “to " awkward, hence the Latest Proposal above.

For example, radial-gradient(5em circle at 25% 50px, white, black)

Comparison to other proposal:

Examples
Alternate Proposal	Current ED
`radial-gradient(white, black)`	`radial-gradient(white, black)`
`radial-gradient(ellipse farthest-corner at center, white, black)`	`radial-gradient(ellipse to farthest-corner at center, white, black)`
`radial-gradient(at top left, white, black)`	`radial-gradient(at top left, white, black)`
`radial-gradient(farthest-corner ellipse at top left, white, black)`	`radial-gradient(ellipse at top left to farthest-corner, white, black)`
`radial-gradient(5em circle, white, black)`	`radial-gradient(to 5em, white, black)`
`radial-gradient(5em circle at center white, black)`	`radial-gradient(circle to 5em at center, white, black)`
`radial-gradient(closest-side circle at 75% 75%, white, black)`	`radial-gradient(circle at 75% 75% to closest-side, white, black)`
`radial-gradient(15px 30% ellipse at 25% 2em, white, black)`		`radial-gradient(ellipse to 15px 30% at 25% 2em, white, black)`