[3.0] Theme split (wave 4, part 32) — point the overlays and alternating rows at design tokens

[albertlast]

Description

Part of the #7933 split.

The help pages, the tooltip, the popup content frame, the generic list grid, the striped and alternating row backgrounds, the two-factor code block, backtrace separators and the diff output colours. 33 tokens. Every token holds the value the rule has today, so nothing renders differently.

.stripes:nth-of-type(even) and .alternative both carry #f2f2f2 but are separate devices used in different places, so each gets its own token rather than sharing one — the rule from #9448 about one value carrying two meanings.

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.