test(a11y): focus outline being cut off on dropdown and overflow-menu components within docs

[mfranzke]

Currently the focus outline is being cut for dropdown and overflow-menu components off within our documentation.

• https://db-ui.github.io/core/patterns/components-dropdown/index.html
• https://db-ui.github.io/core/patterns/components-overflow-menu/index.html
• https://db-ui.github.io/core/?p=viewall-areas-header

WCAG 2.4.7 Focus Visible (Level AA)