Stop the report tab row from becoming scrollable

[str1fe]

On /reports the row holding the tabs (Tasks, Team members, …) rendered a scrollbar even though the tabs fit, which looked out of place.

Cause

The tab links carry -mb-px so the active underline sits on top of the row's bottom border. Since the links live inside the overflow-x-auto container, that negative margin makes the content 1px taller than the container's content box (measured clientHeight 45 vs scrollHeight 46). overflow-x: auto also turns overflow-y into auto, so the 1px of vertical overflow was enough to produce a scrollbar.

Fix

Move the negative margin to a new inner scroll wrapper and keep the border and padding on the outer element:

• the active underline still overlaps the row's border, so the look is unchanged;
• nothing overflows vertically inside the scroll container, so no scrollbar appears;
• the row can still scroll horizontally on narrow phones, where four long tab labels (e.g. "Teammedlemmer") don't fit — now with no-scrollbar, matching the pattern already used in _sidenav.html.erb.

Testing

Verified the geometry in a browser on an isolated copy of the same markup and CSS: clientHeight/scrollHeight are now 46/46 and clientWidth/offsetWidth 600/600, i.e. no overflow and no scrollbar gutter. The change is markup-only and touches one partial.

🤖 Generated with Claude Code