Type | Object |
---|---|
Mandatory | No |
Example |
"theme_experiment": { "stylesheet": "style.css", "colors": { "popup_affordance": "--arrowpanel-dimmed" }, "images": { "theme_toolbar": "--toolbar-bgimage" }, "properties": { "toolbar_image_alignment": "--toolbar-bgalignment" } } |
This key enables the definition of experimental theme
key properties for the Firefox interface. These experiments are a precursor to proposing new theme features for inclusion in Firefox. Experimentation is done by:
- creating a stylesheet that defines mappings between internal CSS selectors for Firefox UI elements and arbitrary CSS variables. The CSS variables are then mapped in the
colors
,images
, andproperties
objects to newtheme
key properties. - (without a stylesheet) using
colors
,images
, andproperties
to map internal Firefox CSS selectors, such as--arrowpanel-dimmed
to newtheme
key properties. This option limits experimentation to UI components that are associated with an inbuilt CSS variable.
To discover the CSS selectors for Firefox UI elements or internal Firefox CSS variables use the browser toolbox.
Note: This key is only available for use in Firefox Developer Edition and Firefox Nightly channels and requires the extensions.experiments.enabled
preference to be enabled. In Firefox 73 and earlier, the extensions.legacy.enabled
had to be used instead.
Warning: This feature is experimental and could be subject to change.