Shadows

Subtle elevation for small elements (toggles, pills)

Strong elevation for modals and lightboxes

Soft lift for floating panels — applied by the .popover-surface class, so popovers should not add a shadow of their own

Four stacked layers under the primary button — a tight contact shadow beneath a wider soft one, so it reads as seated rather than floating.

The secondary button has no border at all — its entire edge is this: an inner ring, a brighter inner top edge (lit from above), an outer ring and a soft drop.