Overflow ancestor constrains sticky

Diagnosis

What this finding means

An ancestor with overflow auto, scroll, or hidden changes the sticky container.

A finding is not a verdict. Check the displayed evidence and the design intent before changing production code.

Detection

How CSS Doctor detects it

1. CSS Doctor isolates the pasted HTML and CSS in a sandboxed iframe.
2. Static rules inspect source structure; runtime rules measure the rendered result.
3. Evidence is ranked by intent, severity, confidence, affected area, and fix safety.

Before / After

Minimal example

Review the rendered element and its ancestors.

Choose the narrowest change after comparing before and after.

The example is a starting point, not a universal patch. CSS Doctor previews Tier A and B changes before applying them and never auto-applies Tier C guidance.

Limitations

Limits and manual checks

Removing overflow can create another defect, so this rule is advisory.

• Production stylesheets not pasted into the tool are not fetched.
• JavaScript is never executed from user input.
• Verify the result at all breakpoints and with keyboard input.