Remove the card behind burned-in captions: colors.card null

To remove the card behind burned-in caption words, send design.colors.card as null in the Sume caption request. The video captions page lists card among the colors fields and notes that null shows no card. It applies only to styles that read design tokens: punch and tiktok-green do not support design at all, because they render on a path that reads none of the tokens.

The request

Pick a style that supports design, such as weight-shift or pill-karaoke, and override one token. Sume merges each field over the style's own value, so one key changes one thing.

{
  "video_url": "https://example.com/clean.mp4",
  "style": "pill-karaoke",
  "design": { "colors": { "card": null } }
}

Which styles it helps

The docs do not promise that every style draws a card, so test one short clip before a batch. A style with no card has nothing for null to remove.

Rules that apply to every override

• Colors are hex, rgb(), rgba() or transparent. Other CSS syntax is rejected.
• A number outside its documented range returns a 400, so a wrong look fails at request time and you do not pay for an incorrect render.
• To keep the original video and only change the look, send source_caption_id and not video_url. Sume reuses the stored word timings, so speech-to-text does not run twice, and the price is the same because a restyle is still a render.
• transparent is a different choice from null. The docs describe null as showing no card.

Combine it with other tokens

The design groups are colors, typography, placement, phrasing and motion. A card-free look often needs a stroke so the words read on busy footage: set colors.stroke and typography.stroke_width_px in the same request.

Check the placement.anchor_ratio, which is the center of the line as a fraction of the frame height, so the words stay out of platform UI. Sume does not state where that UI sits, so check the platform's own pages.