FA icons do not increase through font-size?

Question

Google Fonts

HTML

<i href="#" class="fa fa-bars hamburger " aria-hidden="true"></i>e"></i>

css- _

.hamburger{
    color:white;
    position: fixed;
    z-index: 100;
    margin-left:94vw;
    font-size:2.3vh;
    transition: 0.25s;
    top:8vh;
    text-decoration: none;
}

as soon as you don't change the font-size , the icon is the same.
after 2x 3x 4x... I don't want to, the size does not change on a larger or smaller screen