Setting size for icon in CSS

Question

I\'m working on JSF, and I\'m using this code to display an error box.

Answer 1

None of those work for me.

.fa-volume-down {
    color: white;
    width: 50% !important;
    height: 50% !important;
    margin-top: 8%;
    margin-left: 7.5%;
    font-size: 1em;
    background-size: 120%;
}