Our phone layout check said 0 overlaps. The check itself was wrong.

What we believed

A green result from our own layout checker meant the phone layout was clean.

What we did

Wrote an automated check for three demo web pages: emulate a phone, scroll through the page step by step, and compare every image's bounding box with every line of text, link, button and form field. Widths 360, 375, 390, 414 and 430, with normal and reduced motion.

Reality

• The check reported 0 overlaps.
• Its measuring was broken. It scrolled with smooth scrolling, so each step was measured while the page was still moving, not where it settled. The 0 could not be trusted.

What changed

• The check now uses instant scroll and was rerun on all 5 widths, normal and reduced motion.
• We added a second check for text showing through the sticky header.
• Rule: verify the checker before trusting its green light.

Explicit non-claims

• This does not say the pages are now perfect. The rerun still has documented exclusions (text deliberately placed over background images), and it ran in an emulated browser, not on a real phone.
• Demo pages, not client work. No revenue from this.