Keep WebVTT comments and stylesheet blocks out of dialogue

The useful distinctions

• WebVTT supports NOTE blocks for comments.
• STYLE blocks carry cue styles and precede cue data.
• The ::cue selector applies a permitted subset of CSS properties.

Identify each block's job

The first block after the signature is an editorial note, the second contains a cue stylesheet, and the third is timed dialogue. Only the last block supplies the words associated with a time interval. A pipeline that flattens all nonempty lines into captions would accidentally display both the note and CSS. Preserve block types during ingestion so an editor can inspect comments without treating them as content.

Use styles as a separate authoring layer

The sample requests white cue text on a dark background with the cue selector. It does not attempt page layout or style arbitrary video-interface controls. A subtitle exporter should serialize the stylesheet in its proper location before cues, and a review should reject constructs that the cue styling subset does not admit. Keep the note free of the timing arrow token so it cannot resemble a malformed timing block. If an intermediary removes styles, the underlying dialogue and cue interval should remain identifiable. That separation gives a useful failure check: compare the cue ledger before and after a style-only edit and confirm that neither the words nor timestamps changed. Visual appearance still needs a rendering review where presentation fidelity matters.

Worked example · synthetic

The note has no timestamp and is not cue dialogue. The stylesheet precedes the cue; the only timed payload is the final sentence. The example makes no claim about a particular browser's rendering.

Synthetic text example; no network operation has been performed.

WEBVTT

NOTE Editorial check: retain the colour name.

STYLE
::cue { color: white; background-color: #202020; }

00:00:02.000 --> 00:00:04.000
Choose the violet sheet.

Check the interpretation

• Keep STYLE before the first cue.
• Recognize NOTE as a block rather than dialogue.
• Confirm style edits leave the cue ledger unchanged.