Why is only one flexboxgrid class pulling styles in the browser?

Question

css

I have a project on rails (maybe it has some meaning). As a grid, I decided to use the flexbox grid flexboxgrid The manual says that you can write classes like col-xs-12 col-sm-8 in one line (and so on, as in bootstrap straight) and there will be happiness - depending on the resolution, it will work this or that class and change the width of the block. I did everything according to the instructions. The result - in the browser (any) only the col-xs-12 class is pulled up. How is that? Some kind of magic ... It seems that the viewport is not tracked, although I have a meta tag in my head

meta name="viewport" content="width=device-width, initial-scale=1

Everything works in the codepen , what is wrong with me and my project?!))

Answer 1

The issue was resolved by installing gem 'autoprefixer-rails'