Element Size Rules от VilleKokkarinen

Element Size Rules lets you customize the layout of websites with your own CSS. Create rulesets for specific sites or pages, choose elements with the visual picker, and adjust the selected element’s parent or child before saving.
- Match rulesets to pages using wildcard URL patterns.
- Add CSS manually or pick an element to create a selector.
- Edit, enable, disable, or delete rules and rulesets.
- Start with the included YouTube “4k” sample ruleset, and customize or remove it.
Rules are stored with Firefox Sync and may sync across devices when add-on syncing is enabled.