[core] Batch small changes

[oliviertassinari]

• [docs] Remove duplicated ids e286a5b: Help with https://validator.w3.org/nu/?doc=https%3A%2F%2Fnext.material-ui.com%2Fcomponents%2Fslider-styled%2F

• [breakpoint] Fix NaN value 052a813: Help with https://validator.w3.org/nu/?doc=https%3A%2F%2Fnext.material-ui.com%2Fcomponents%2Fslider-styled%2F

• [test] Lowercase to match BrowserStack API results 4741b07: The API: https://www.browserstack.com/docs/automate/api-reference/selenium/browser#get-browser-list
• [docs] Use px f7acfbc: To match 8e280c2#diff-c743b3b575d4f5b5345f50876aedc6c1R114

[mui-pr-bot]

Details of bundle changes

Generated by 🚫 dangerJS against f7acfbc

[stefaluc]

@oliviertassinari Is there any way this could be included in the stable release as well (particularly 052a813), or would that be against your current release workflow?

[oliviertassinari]

@stefaluc The objective of this commit was to simplify the logic (remove code), not to improve the behavior. doing down('xs') doesn't make sense, as far as I understand it.

[stefaluc]

@oliviertassinari Thanks for the prompt response! I am trying to set custom breakpoints in my application but am receiving NaN values in my media queries. It looks like I mistakenly assumed this PR as the fix for this issue, when in actuality it looks like #21759 may be the fix I am looking for. So, same question, but with regards to #21759 instead 😁

[oliviertassinari]

@stefaluc Honestly, we have done many iterations on improving the support for custom breakpoints. Even on v5, I suspect there are still issues.

[stefaluc]

@oliviertassinari Hmmm, I guess I'll just implement my own breakpoints outside of MUI then. I'd love to contribute if I can, but you saying that it's gone through many iterations leads me to believe that it would lie outside of my ability to make improvements.