1
Display Toggling
Detects when elements switch between display values (none, block, flex, grid, inline) affecting their presence in the layout.
25 test cases
Visibility & Opacity
Visibility changes can make content appear or disappear unexpectedly. Whether it is a hidden error message that stops showing, or an element that becomes invisible due to a CSS conflict, Delta-QA catches every visibility state change.
What we detect
2
Visibility Property
Catches visibility:hidden changes where elements become invisible but still occupy space in the layout.
3
Opacity Changes
Monitors opacity variations from fully transparent (0) to fully opaque (1), including partial transparency.
4
Z-index Reordering
Detects stacking context changes where elements overlap differently due to z-index modifications.
5
Overflow & Clipping
Identifies overflow behavior changes (visible, hidden, scroll, auto) that can hide or reveal content.
Live example
See exactly what Delta-QA detects. Compare the two versions side by side.
Before
After
Real-world scenarios
🎯
The promo banner that disappears
A developer reworks the header and adds overflow: hidden on the parent container. The promo banner "-20% with code SUMMER" is still in the code, but visually it's clipped — invisible on screen. Your visitors don't see the promotion, you lose sales for days. The team trusted the test pipeline — the banner exists in the DOM, tests pass green. Delta-QA compares screenshots and detects the banner's disappearance — the empty space at the top of the page jumps out immediately in the diff.
⚠️
The z-index that hides a button
A developer integrates a chat widget with a z-index of 9999. On mobile, the widget lands right on top of the floating "Buy" button at the bottom of the screen. The button is still in the code but visually hidden behind the chat — your customers can no longer purchase. The tester checked on desktop, not on mobile where the elements overlap. Delta-QA compares mobile screenshots and detects the "Buy" button is covered by the widget — the masked area stands out in the diff.
💡
The opacity that makes text unreadable
A developer reduces the opacity of the dark overlay on the hero image to "show more of the photo." The white text ends up on a background that's too light — it becomes nearly unreadable. Your visitors can no longer read the main message on the homepage. The change seemed cosmetic, the developer merged it thinking it looked better. Delta-QA compares screenshots and highlights the text that became unreadable — the lost contrast between text and background stands out clearly in the overlay.
Ready to catch every visual regression?
Download Delta-QA and start detecting CSS changes in your web pages — no code required.