That said...it appears that the use of CSS custom properties may not be wise based on current browser support for that feature. Is that the case?
On Thursday, 16 July 2015 15:21:33 UTC-7, Kelly St. John wrote: > > Thanks Justin. I just read more of the Styling documentation from the > Styling section of the 1.0 Developer Guide. Here is an important extract > pertaining to my issue (see below). It seems application-wide 'theming' > capability is a bit of a casualty stemmed from the necessary removal of > /deep/ and ::shadow selectors used previously in polymer 0.5. As you > eluded to above, it seems I'll have to look into how to incorporate the use > of Custom CSS properties in order to apply 'theming' across elements. > > "One solution the Shadow DOM spec authors provided to address the theming > problem are the /deep/ and::shadow combinators, which allow writing rules > that pierce through the Shadow DOM encapsulation boundary. Although Polymer > 0.5 promoted this mechanism for theming, it was ultimately unsatisfying for > several reasons: > > - > > Using /deep/ and ::shadow for theming leaks details of an otherwise > encapsulated element to the user, leading to brittle selectors piercing > into the internal details of an element’s Shadow DOM that are prone to > breakage when the internal implementation changes. As a result, the > structure of of an element’s Shadow DOM inadvertently becomes API surface > subject to breakage, diminishing the practical effectiveness of Shadow DOM > as an encapsulation primitive. > - > > Although Shadow DOM’s style encapsulation *improves* the > predictability of style recalc performance since the side effects of a > style change are limited to a small subset of the document, using > /deep/ and::shadow re-opens the style invalidation area and reduces > Shadow DOM’s effectiveness as a performance primitive. > - > > Using /deep/ and ::shadow leads to verbose and difficult to understand > selectors. > > For the reasons above, the Polymer team is currently exploring other > options for theming that address the shortcomings above and provide a > possible path to obsolescence of /deep/ and ::shadow altogether." > > > > On Thursday, 16 July 2015 14:15:58 UTC-7, Justin Fagnani wrote: >> >> >> >> On Thu, Jul 16, 2015 at 1:57 PM, Kelly St. John <[email protected]> wrote: >> >>> On a somewhat related note, is there a reason the demos/docs are not in >>> place for paper-styles in the new 1.0 element catalog? ( >>> https://elements.polymer-project.org/elements/paper-styles) >>> >>> Should I be using paper-styles, or is it experimental? >>> >> >> It's not experimental. I'm not sure why the documentation isn't showing >> up. >> >> >>> >>> >>> >>> On Thursday, 16 July 2015 12:39:25 UTC-7, Kelly St. John wrote: >>>> >>>> Hi All, >>>> >>>> I'm currently in the midst of migrating an app built on polymer 0.5.4 >>>> to 1.0. In the 0.5 app I leveraged the core-style element throughout in >>>> order to apply common styling amongst the various custom elements. I'm >>>> not >>>> a CSS expert by any means (a relative newbie actually), and could really >>>> use an example of how to do the same using the new 1.0 styling paradigms. >>>> I like the idea of using a document-level element (via an external html >>>> file) to store application-level common styles. For instance, one would >>>> presume I could then place something like this in that document level >>>> external file: >>>> >>>> <style is="custom-style"> >>>> >>>> .center { >>>> @apply(--layout-center); >>>> } >>>> >>>> .horizontal { >>>> @apply(--layout-horizontal); >>>> } >>>> >>>> .vertical { >>>> @apply(--layout-vertical); >>>> } >>>> >>>> >>>> </style> >>>> >>>> >>>> And use these document level styles by applying classes to any tag in >>>> the app, like: >>>> >>>> <div class="horizontal center"> >>>> >>>> However, that approach doesn't seem to be working at the moment. >>>> >>> >> This is as intended. The styles are scoped on purpose so that they don't >> leak downward. It's totally possible that in some component you're using >> that .center is supposed to have a slightly different styling (especially >> considering how many ways there are to center), and you wouldn't want to >> override it. >> >> The correct approach is to apply the properties where you need them. In >> the host of that <div>, use @apply: >> >> .my-class { >> @apply(--layout-center); >> } >> >> <div class="my-class"></div> >> >> If you want to pass styles down the tree, and through scope boundaries, >> then you can use CSS custom properties, but it's always up to the element >> in a scope to choose to apply the property. In that way it's opt-in from >> the element's point of view. >> >> Does that help? >> >> Cheers, >> Justin >> >> >> >>> I'm likely missing something with the scoping of CSS styles in Polymer >>>> 1.0, or maybe even barking down the wrong path entirely. I want to employ >>>> a theming strategy that will continue working as Polymer evolves beyond >>>> 1.0. I do not want to rewrite this application anytime soon...or it will >>>> likely be necessary for me to look for other employment. Can someone >>>> kindly point me in the right direction, please? >>>> >>>> Thanks >>>> >>> Follow Polymer on Google+: plus.google.com/107187849809354688692 >>> --- >>> You received this message because you are subscribed to the Google >>> Groups "Polymer" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/polymer-dev/3759a8f4-2da7-4fca-b51a-77f57d2d8d8f%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/polymer-dev/3759a8f4-2da7-4fca-b51a-77f57d2d8d8f%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> Follow Polymer on Google+: plus.google.com/107187849809354688692 --- You received this message because you are subscribed to the Google Groups "Polymer" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/polymer-dev/a071aece-1937-42fb-8d5c-c972a52c7b77%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
