Standardize marquee UA styles. #10249
Description
What is the issue with the HTML Standard?
Other than the spec's https://html.spec.whatwg.org/#the-marquee-element-2, engines have some extra marquee styles:
Gecko has:
marquee {
inline-size: -moz-available;
vertical-align: text-bottom;
white-space: nowrap;
}Plus:
marquee:is([direction="up"], [direction="down"]) {
block-size: 200px;
white-space: unset;
}Blink has here and here something like:
marquee {
width: -webkit-fill-available;
white-space: nowrap;
}
And:
marquee:is([direction="up"], [direction="down"]) {
white-space: initial;
}(Note that the overflow rules in there are redundant because they get overridden in here, so they match the spec).
WebKit has this which IIUC is something like:
marquee:not([direction="up"], [direction="down"]) {
white-space: nowrap !important;
}Plus a special "if height is auto, set height to 200px for vertical marquee".
I think something like this might be a good common denominator to be added to the current spec:
marquee {
inline-size: stretch; /* -moz-available / -webkit-fill-available */
white-space: nowrap;
}
marquee:is([direction="up"], [direction="down"]) {
block-size: 200px;
white-space: unset;
}So:
- Gecko would remove vertical-align.
- Blink will use logical properties for stretch sizing and add the default vertical marquee size, plus use unset (inherit) rather than initial for white-space, which I think it's more in line with the expectation of authors.
- WebKit won't use magic adjustments (except for overflow if they want I guess where it's not observable).
Does that seem reasonable?