How to blur background when bootstrap modal opens?

Question

css

As I understand it, the class is responsible for the background of the modal modal-backdrop, I thought you can do this

.modal-backdrop
{
    filter: blur(8px);
    -webkit-filter: blur(8px);
}

, but it doesn't work. How can I blur the background?

Answer 1

https://bootsnipp.com/snippets/a6Kz3