Why a cookie banner flashes before it disappears, and how to stop it
Some blockers hide the banner a moment too late, so you watch it appear and then vanish. It reads as a bug.
Hiding rules are registered to apply before the browser parses the page, and the on-page bundle is kept deliberately tiny so it runs early.
Why the usual fixes do not stick
The flash is a timing problem, not a rules problem. If the hiding CSS is fetched, or is sent by a background script after the page has started painting, the banner has already been on screen for a frame or two before it goes. The fix is to have the rules already present when the document starts: a small script at document_start reads a cached snapshot synchronously and installs the stylesheet before first paint.
How to do it with BowerBird
- Nothing to configure. It is how the rules are installed.
Worth knowing: Measured on five real sites at four times CPU throttling, the rules landed before first paint in every sample. On a first visit to a site that redirects to a different subdomain, one flash is still possible.
Without granting access to every site you visit
BowerBird installs without asking to read or change your data on any website. Its ad and tracker blocking runs on rules the browser applies itself, which needs no site access at all. When you hide your first element on a site, it asks for that one site, from your click, and you can revoke it later in settings.
Hide your first annoyance free - no account, no subscription.
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