[3.0] Theme split (wave 4, part 29) — point the BBC tags at design tokens

[albertlast]

Description

Part of the #7933 split.

The quote citation, the quote and code headers, inline code, BBC tables, the details/summary tag and the inline spoiler's focus ring — the hard-coded values left in the BBC section of index.css. 13 tokens. Every token holds the value the rule has today, so nothing renders differently.

.bbc_table and .bbc_table th, .bbc_table td share one --bbc-table-* set: it is one grid drawn with one line weight, and giving the cells their own tokens would let the two drift apart silently.

Verification

Every rule in index.css parsed out of the file as text, applied to a probe, read back as a fixed list of 57 longhands:

965 rules, 55,005 computed values, 0 differences.

Issues References (Fixes|Related|Closes)

Related: #7933

[albertlast]

Re-ran the verification, because the first run was taken on ?topic=1.0 and that page is a fatal on release-3.0 — Object of type SMF\TimeInterval (inheriting DateInterval) has not been correctly initialized by calling parent::__construct(), which is #9405 and not merged yet. An error page still loads variables.css, and base and branch were captured in the same state, so the comparison held; but it is not a measurement anyone should have to take on trust.

Repeated on ?action=recent, which renders, with the capture now recording the page URL, whether #fatal_error is present, and the list of loaded stylesheets so a broken page cannot pass unnoticed:

OK  page=/index.php?action=recent fatal=False  965 rules, 55005 values, diffs 0

Same result. No change to the diff.