[Header] Low contrast between header and background

**Description**
The contrast between the header and the background might be too low, affecting readability and visual clarity. This will automatically improve with the #783

This task is ment as a reminder to consider revisiting the color theme of the header as a potential improvement after the release.

**Desired outcome**
The header should have sufficient contrast against the background to ensure good readability and alignment with accessibility guidelines.

Review issue #783 first, since the issue says the contrast may improve through that work. Then identify the header and background colors in the component implementation and evaluate them against accessibility contrast guidance; done means the header is readable and has sufficient contrast after the release.

Written by the indexing model from the issue text.