Two site-wide interaction failures traced to browser behavior, not buggy code

A development team experienced two separate incidents where their website appeared fully loaded but was completely unresponsive to user clicks and taps. The first issue stemmed from an AI chat widget configured to open automatically on page load, which applied the HTML 'inert' attribute to all other page elements, blocking all interaction by default. The second incident involved a floating WhatsApp button whose large transparent container was intercepting roughly 35% of the mobile screen's touch area, a problem misdiagnosed due to incorrect use of the CSS pointer-events property on the child element instead of the parent. In both cases, automated tests passed without detecting the failures because standard checks for visibility and DOM presence do not account for inert state or touch interception. The team recommends using elementFromPoint() to identify which element truly receives input, and adding explicit test assertions to confirm no unintended inert attributes exist on page load.