Minify CSS, JS is very common task for website load time optimization.
Read this tutorial to minify your CSS, JS, SASS, LESS files on windows by “Koala”.
Step:1 Download it from http://koala-app.com/
Step:2 Open Koala (Start->Koala->Koala.exe”) and drag and drop your working folder in Koala like this:
Step-3: Click “refresh” to see all CSS, JS, LESS, SASS files list