Changed icon label color from white to dark red (--accent-red-deep)
for readable contrast against the sand background. White color and
text-shadow now only apply on hover when the colored background is
present. Replaced the expand-all-on-box-active behavior with an
individual .expanded class for touch devices, and removed the brief
:active pseudo-class that was barely visible on tap.

Replaces the expand-all-on-section-tap mobile behavior with a
per-icon tap interaction that matches desktop hover UX: first tap
expands the icon and reveals its label, second tap navigates to
the link. Tapping outside or on another icon collapses the previous.