There are different kinds of section headers throughout the (side) panels which basically stand for the same thing.

They always contain a headline text and have a lighter background than the surrounding UI and a border at the top and bottom.
Sometimes they are foldable like in the accordion widget and/or may contain additional elements like a toggle button.

Currently used section headers:

• Rules view in Inspector: headers separating pseudo-element styles (foldable), the current element's styles, and inherited styles
• Layout view in Inspector: headers for different layout types and box model (accordion widget)
• Compatibility view in Inspector: headers for selected element and issues (accordion widget)
• Fonts view in Inspector: header for all fonts on page (accordion widget)
• Changes view in Inspector: headers for files
• Sidepanel in Debugger: headers for watch expressions, different kinds of breakpoints, call stack, and scopes (accordion)
• Headers view in Network Monitor: headers for request and response headers (accordion)
• Cookies view in Network Monitor: headers for request and response cookies (accordion)
• Request view in Network Monitor: headers for request data display (accordion)
• Response view in Network Monitor: headers for response data display (so far accordion, after bug 1651649 not anymore)
• Timings view in Network Monitor: header for timing statistics
• Data view in Storage Inspector: headers for general data and parsed value
• Accessibility info in Accessibility Inspector: headers for checks and properties (accordion)

This bug is meant to create the widget which can then be shared across the different panels.

Sebastian

Thanks for the report Sebo.

Moving to "Shard components" since it feels more appropriate.

Honza

(In reply to Jan Honza Odvarko [:Honza] (always need-info? me) from comment #1)

Moving to "Shard components" since it feels more appropriate.

Oh, yeah. I initially thought it would be enough to change the CSS but then saw that there should rather be a centralized widget and forgot to change the component.

Sebastian