Why css files are opening in safari by default in MacBook?

I do not know what happened to my MacBook, but all the css files are appearing with the web browser icon as you can see in the following image. When I open it it is opening in safari instead of TextEdit/other any editor. This is not happening with other file like .php, .twig, .yml, those all are opening in Text file? Any idea why this is happening and how to correct that? Besides, in-built TextEdit of Mac, I am also using TextMate Editor(latest version 2.0).