Debugging overflow: find the box that is wider than the viewport
Horizontal overflow is diagnosable when you inspect the widest box instead of adding overflow hidden to the page.
Debugging
Debugging
Triage guides for the CSS failures that slow real projects down.
Z-index triage: debug stacking contexts before raising numbers
If z-index is not working, the element is usually inside a stacking context that matters more than the number.
Debugging layout shift in CSS-heavy interfaces
Layout shift is usually a missing reservation of space, not a mysterious browser event.
Responsive breakpoint failures: debug the component, not just the viewport
If a component fails between named breakpoints, the breakpoint probably describes the screen better than the component.