Applying Custom CSS with Puppeteer

When running automated tests with Puppeteer, my test site occasionally triggers info alerts for success or error messages. These alerts often cover the buttons my script needs to interact with, causing issues during testing. I want to inject my own CSS to hide these distracting popups. Does Puppeteer have a built-in feature that lets me include custom styles dynamically to prevent these overlays from interfering with test automation?

In my experience, Puppeteer itself does not provide a direct built-in function purely for injecting custom CSS that hides overlays, but it easily supports script and style injection. I solved a similar problem by using page.addStyleTag immediately after navigating to the page. The custom CSS I injected was designed to hide your specific popup elements while leaving other elements intact. This approach proved very reliable in preventing those overlays from interfering with test actions.

hey, u could try inserting a style element via page.evaluate. i did that in my tests and it hid my annoying popups quickly. u just gotta tweak your css selectors accordingly.

Although the common techniques involve adding style tags dynamically, I found that employing a MutationObserver inside page.evaluate works exceptionally well in more unpredictable environments. In my tests, I injected a script that continuously watches for new elements matching the alert criteria and removes them as soon as they appear. This solution has proven robust when successive test runs triggered unexpected overlays. It allowed my automation to proceed smoothly without having to hardcode every possible alert and minimized maintenance when the site changes over time.

I solved a similar problem by injecting custom CSS in a slightly different way than using addStyleTag after page load. In my tests, I found using page.evaluateOnNewDocument to insert the style element provided a more consistent solution, as the styles were applied before any of the DOM content was rendered. This approach prevents any overlay from showing up in the first place, simplifying subsequent interactions with page elements. The injection is executed immediately when the page starts loading, which minimizes the chance of overlay interference regardless of page changes or test conditions.

hey, i solved it by using page.addStyleTag with inline css including !important rules to hide the alerts. sometimes playing with z-index also did the trick. works pretty well for my tests, so might be a neat solution for your issues too.