static/style.css no longer holds every rule. 79 rules for the document,
gallery and editor panels now live in static/css/, yet 27 browser tests still
built their synthetic page with a single <link> to style.css, and 51 more read
that one file as though it were the whole cascade. Those tests kept passing
while covering less: a rule that moved became invisible to the assertion that
was meant to pin it.
Python readers now call tests.helpers.stylesheets.app_css(), and synthetic
pages are built from stylesheet_link_tags() so they load exactly what
index.html loads, in the same order. The helper already existed; this moves
the remaining callers onto it.
test_portal_dropdown_z_js parametrised over a file list including style.css to
assert an absence. Checking a negative against one file of a split stylesheet
is how a moved rule escapes, so the CSS case now checks the concatenation.
Two guards keep it from coming back: one fails on any test reading
static/style.css directly, the other on any synthetic page linking it alone.
Both name the helper to use.
No production code changes. Suite is unchanged at 6 pre-existing failures.
Léo