Set the colours and theme options used across the branded experience, and optionally replace the account's logo. Send JSON for theme options only, or multipart/form-data with logo_image. The response has the saved theme plus the account's white-label record, with image fields as full URLs.

Prerequisites: a bearer token, the company_id of the account you're theming, and your user id (user_id). To upload a logo: a JPEG or PNG up to 400 KB.

Authentication: Partner or Account token. company_id must be inside your own account tree (a Partner token reaches any account under the partner, an Account token only its own); otherwise 422. user_id is recorded as who saved the theme; send your own.

Rate limit: none.