The style.css inside magento installation directory is effecting cache

I am very new to Magento. Recently i have to add extra styles to my magento website. So I go to adminpanel -> content-> design->configuration->my theme ->HTML Head

I add the following line

<link rel="stylesheet" type="text/css" media="all" href="" /> 

Then I save that one. Now new styles are working on my website. But I edited some of the styles through opening the file through Filezilla and edit. After that, I uploaded. Then I noticed that new changes are not coming. So I open in a browser so I can see that it is not updated the copy. I refresh the page and I open in incognito window. Still the same. But when I open in the same file through editor using FileZilla I can see that it is updated copy.

Then I try to refresh page cache, layout cache but the result is the same.

Please help.