# 31 — ARRFLIX theme layer model + edit guide (2026-05-09) > **Read this before editing any CSS in `bin/inject-middle-theme.py`, `web-overrides/index.html`, or `branding.xml`.** Five black-screen-over-video incidents in 24 hours (doc 26 INC1–INC5, doc 28 INC7, doc 30 v6-stable, plus this latest one) all came from the same anti-pattern: an opaque `background-color` rule painted on an ancestor of `