Icon color in button-icon

html:

<button class="button light ion-plus-round button-floating-action"></button>

css:

.button-floating-action {
    position: fixed;
    top: calc(90vh - 50px);
    right: 2vw;
    background-color: #ef473a;
    border-radius: 100px; 
    border-width: 0; 
    padding: 5px 12px 5px 12px;
    z-index: 999;
    box-shadow: 5px 5px 5px #888888;
}

got it working for me.
hope that helps!