Only the active tab now breaks the bottom rule (up, across open, back
down); inactive tabs sit flush against it with no corners or seams of
their own, so they read as behind/in-the-dark rather than each having
their own raised box. Top border and its z-order layering (active tab
always wins both corners) are unchanged. Adds a 2-column left margin
when the width has slack for it.
Tab switching moves off the shared Left/Right handler onto Tab/Shift+Tab
only, freeing the arrow keys for other use on this screen.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Jean-Pierre MartineauandClaude Sonnet 5
d1c2df61c9