Slide 0: Viewport-Fit Pass

This slide correctly uses height: 100dvh; overflow: hidden. The validation script should report no overflow here at any breakpoint.

Slide 1: Intentional Overflow

FIXTURE: This inner div is 2000px tall.
overflow: visible is set on the parent .slide.
scrollHeight will exceed clientHeight at every breakpoint.
validate-slides.py must report this slide as overflowing.
Expected exit code: 1
If validate-slides.py exits 0 on this file, the detection logic is broken.