As you update plugins and themes, your site could go through unwanted visual changes that you won’t always be able to catch quickly. VRTs for WordPress can help. The Visual Regression Tests plugin lets you test your site for unwanted visual changes. It runs daily and creates daily comparison screenshots and compares them to your main snapshot.
This plugin tests your pages and posts and sends you instant alerts when changes are detected. Once you have fixed the issue, you can create a new snapshot for future tests. The free version tests up to 3 pages while the pro version allows tests for 25 pages. The pro version can also alert multiple users.