Prepare CSS section for Markdown conversion

[SphinxKnight]

• Remove summary and seoSummary classes
• Deal with hidden code blocks in live samples
• Remove hidden div/paragraphs for interactive examples
• Remove hidden elements that don't contain code blocks in a live sample
• Remove id attributes except on headings
• Remove notranslate class
• Convert/fix note/warning cards
• Fix broken dd elements
• Deal with sup and sub
• Remove nested partial strong in code
• Deal with <div class="index">
• Fix live samples that use IDs which are not derived from heading text
• Remove random CSS classes and unsupported elements
• Remove links with deki
  (list shamelessly plagiarized from [Markdown] Preparing CSS docs for Markdowning content#5865 )

[SphinxKnight]

Note for review: I intentionally left some <sup>s and <sub>s for French typography consistency

[SphinxKnight]

@tristantheb I'm sorry to inflict this on you :x
I guess checking the conversion report on your side after running yarn run md h2m web/css --locale fr --mode dry and checking a sample of pages should be enough?

N.B. I don't know why there is a dl which is not handled for CSS Counter Styles :/

[wbamberg]

N.B. I don't know why there is a dl which is not handled for CSS Counter Styles :/

There's a bug in the converter where it will fail to convert <dd> elements that have some content (like a list, or a code block) which is not preceded by some text. See mdn/yari#4307 .

In practice, every instance of this that I have seen would be improved by adding some text explaining what the nested list is, or by reworking the markup entirely.

In this case I replaced the whole <dl> with a nested list, which was more consistent with other CSS module pages and seemed to have better semantics (the list of at-rule descriptors do not define the at-rule): https://raw.githubusercontent.com/mdn/content/main/files/en-us/web/css/css_counter_styles/index.md .

[SphinxKnight]

Thanks @wbamberg :) I was looking at the wrong commit on the English side. (fwiw, it's really helpful to look at the state of things at the last commit (before conversion) on the mdn/content repo (to apply similar fixes on French), maybe a git tag would be helpful, I'm not 100% sure)

Here is the conversion report after all this: https://gist.github.com/SphinxKnight/87da8b54884a035e27a2556bd91a33e4

A few notes:

• <sup>/ <sub> are left for typography (the ones in mathematical expressions where a ^ was acceptable were removed)
• <i lang="en"> is left as well, again for typography in French.