Testing appearance

Use fxcss check for an audit, screenshots and a combined report. Use shot and compare separately when you want to control each step.

Capture the same browser states before and after a theme change, then inspect what moved or changed colour:

fxcss shot --out shots/before --variants all
# Edit your theme, then capture it again.
fxcss shot --out shots/after --variants all
fxcss compare --base shots/before --head shots/after --out diff/

Keep the Firefox build, operating system and capture settings the same when reviewing a CSS change. For a Firefox update, keep the theme unchanged and capture each browser build with --firefox.