Same email, only the red brand accent changes. The button stays dark blue in every variant (the design system does not allow red buttons). German version, sample data, rendered with Mjml.Net like production.
4px red stripe across the top edge of the white card. Shown as the baseline.
Design system: The design system's “4px brand stripe”.
The top of the card is a solid red header with the logo in white. Everything below stays white.
Design system: Uses red as a brand area around the logo (allowed: “logo area”). Needs a white version of the logo.
The red header holds the logo and the headline in white. The message starts directly with the greeting.
Design system: Bigger brand area. White on red has 5.55:1 contrast, which passes WCAG AA for the 24px headline.
A red band runs across the whole email width at the top with the white logo on it. The white card starts below the band.
Design system: Strongest brand presence. Red stays in the brand area and never touches buttons or links.
No stripe on top. A 6px red bar runs down the full left edge of the card.
Design system: A brand stripe used vertically. Bold but compact; the design system card rules discourage coloured side borders, so it would be an email exception like A.