fix: 🤔 sd-header on multi-theming

[auroraVasconcelos]

Current behavior

• When dark mode is activated, the sd-header docs page does not change

• Samples are not synced with figma, shadows and borders need to be aligned:

Expected behavior

• When switching between themes, the stories should adjust according.
• Figma and code are aligned.

Steps to reproduce

• Go to storybook.
• Open the sd-header docs page.
• Check any different theme.

Technical Information

DoR

• Item has business value
• Item has been estimated by the team
• Item is clear and well-defined
• Item dependencies have been identified

[coraliefeil]

@auroraVasconcelos can this be closed possibly - is it solved by the PR with the header background color?