- From: Tab Atkins Jr. via GitHub <sysbot+gh@w3.org>
- Date: Wed, 18 Apr 2018 17:27:22 +0000
- To: public-css-archive@w3.org
> Coming from conventional html and css and my inferior experience with custom elements and the shadow dom, it doesn't seem natural to me, but I appreciate I'm probably not smart enough to understand the reasons why. A few reasons went into the current design: 1. We purposely didn't involve specificity at all. Doing so would expose implementation details of the component, which makes code fragile - if the component is updated and changes the exact selector it uses, it might start overriding outside rules that previously won, or vice versa, and there's no good way for the component's *user* to understand or manipulate this. 2. So we have to decide in some other way. Document order (the final cascade step) doesn't really work here - it adds an unexpected dependency on exactly how you load the custom element, and might have interesting race conditions. 3. So we're left with Cascade Origin, or something close to it, that just unreservedly makes one or the other win. Actually injecting a new origin into the list didn't seem like a great idea; it's unclear how user vs author stylesheets should interact with this. So instead we add another cascade step for this. 4. And finally, we have to make a decision about which wins. We already know that whatever order we choose, !important should have the reverse order; this is how the cascade origins already work. So we have to decide whether the outer page wins by default, but the component wins in !important, or the reverse. We decided that the former made more sense; this means that the component author's normal styles are "defaults", the component user's styles (!important or not) can override that, and the component author's !important styles can be used to "lock down" styles that need to stay how they are. Going the other way around didn't seem to satisfy use-cases as well: it would mean that component users *can't* override styles by default; they'd have to use !important to do so, possibly interfering with their other styles; and then component authors would have no way of "locking down" styles. -- GitHub Notification of comment by tabatkins Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/2290#issuecomment-382465643 using your GitHub account
Received on Wednesday, 18 April 2018 17:27:23 UTC