Unit tests check logic. Integration tests check API contracts. But neither catches the CSS regression that moves your checkout button off-screen in Safari, or the z-index bug that hides your navigation on mobile. Visual regression testing fills this gap — and with a screenshot API, it's surprisingly easy to set up. The Core Concept Visual regression testing works by: Capturing a "baseline" screenshot of each page/component After each deploy, capturing a new screenshot Diffing the two images pixel-by-pixel Flagging any changes above a threshold as potential regressions The diff highlights exactly where things changed — so you see "the nav bar is 2px taller" or "this button moved 40px to the right" immediately.…