While working with responsive design there are various CSS properties that don't support in all browsers, for that we have to write either common CSS properties that are supported by all modern browsers or write properties specific to the browser. Now the thing is how to test a web page on different browsers and devices, a person or team doesn't own all devices, and not even possible. So to overcome with this we have various online tools available that provide all types of platform and devices for testing. Below are some of them.
1. BrowserStack -- www.browserstack.com
This is free to use to a minute for a test run. If someone wants to spend more time then they can purchase their paid version.
2. Browserling -- www.browserling.com
This is good for cross-browser testing, but this doesn't have the feature to test the browsing on iOS devices.
3. Kobiton -- www.kobiton.com
Kobiton also provide free trial for two weeks, we could first try the product features and then we can decide for subscription.
There are so many other online and offline tools also we have for cross browser testing that can be use. Above are a short list of online cross browser testing tool. Hope this helps you to grab the right information which you are looking for. Thank you!