- Convert tab indentation to 4 spaces in admin/css/admin-styles.css
and admin/css/update-source-selector.css per project coding standards
- Add stylelint and stylelint-config-standard to devDependencies
- Add lint:css npm script to enable CSS quality checking
- Update quality script to include CSS linting
The playground/multisite.html CSS rule-empty-line-before fix was already
applied in commit 3ca2fe5. This PR formally closes the quality-debt
tracking issue by verifying the fix and adding CSS linting tooling to
prevent similar regressions.
Closes#38
