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Breakpoint QA

Responsive Breakpoint Checklist

A practical checklist for auditing CSS breakpoints and validating layout transitions before shipping.

5 min read - Updated 2026-05-13

Use this guide as a compact release reference, then validate the same breakpoints in Sizzy with synchronized devices and screenshot evidence.

Tie each breakpoint to behavior

Breakpoints should exist because the layout needs them. Review every responsive threshold and record which visible behavior it controls.

Navigation collapse and expansion

Grid column count changes

Sidebar and panel visibility

Typography, spacing, and media size shifts

Test around the threshold

A layout that works exactly at the breakpoint can still fail nearby. Test before, at, and after every threshold, then capture evidence for the riskiest routes.

20px below the breakpoint

The exact breakpoint

20px above the breakpoint

The narrowest supported viewport

Release checklist

Every breakpoint has a documented layout purpose.

No route has hidden horizontal overflow.

Navigation, forms, and dialogs work around each breakpoint.

Release screenshots cover the highest-risk breakpoint transitions.