Road names drawn with symbol-placement: 'line' — each glyph
rotated to the tangent of the road it names, dropped when the line bends
past text-max-angle, and repeated every
symbol-spacing pixels. Place names use point placement with
text-anchor and text-offset, and outrank street
names via symbol-sort-key. One collision index spans every
tile, so nothing doubles up across a seam. The toggle flips the map
style, the map chrome, and the page together.