What is html d-flex ?

d-flex is a bootstrap class in HTML, which is used flex classes to control the layout of Bootstrap 4 components. It is the Flexible Box Layout Module, it makes it easier to design a flexible responsive layout structure without using float or position.

 .d-flex {

        display: -webkit-box!important;

        display: -ms-flexbox!important;

        display: flex!important;

    }

The above code is an example of a d-flex class in bootstrap 4.