[3.0] Theme split (wave 4, part 31) — point the personal message styles at design tokens

[albertlast]

Description

Part of the #7933 split.

The mailbox capacity bar and its three fill states, the rule editor's labels, the unread message background, and the unread message and alert lists that hang off the user menu. 15 tokens. Every token holds the value the rule has today, so nothing renders differently.

The capacity bar's three fills use a _empty / _filled / _full suffix on one name, the same shape --progressbar-inner-bg_green already uses for a variant that is a state of the component rather than a state of the pointer.

.pm_unread, .alerts_unread and .unread_notify share one --notifylist-* set: they are one list drawn with one hairline, and separate tokens would let the top and bottom edges drift apart.

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.