Accessibility violations on the marketing header are fixed

The marketing site's header navigation and a few colour combinations across the layout were tripping multiple accessibility audit rules. They are now resolved:

• Muted text colour bumped up to clear the color-contrast threshold against the page background.
• Focus styles restored on the primary navigation so keyboard users can see where they are.
• A missing landmark on the header is now declared with a proper role="banner".

Accessibility is rarely a single dramatic ship — it is a stream of small fixes like this one. The marketing site is now meaningfully closer to passing a clean audit out of the box.