Fix layout buttons being covered by #footerlinks block area

Fix layout buttons being covered by #footerlinks block area

#layout-switcher floats right and appears visually inside the footer row,
but #footerlinks (position:relative, no z-index) came after it in the DOM
and therefore painted on top in stacking order — covering ~80% of the buttons
and making them unclickable except at the very bottom edge.

Adding position:relative + z-index:1 to #layout-switcher puts it above
#footerlinks in the stacking context so all three buttons receive pointer events.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>