JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://netdna.bootstrapcdn.com/font-awesome/3.2.1/css/font-awesome.css">
<div class="widgetbox">
    <br><br>
    <div class="icon-calendar icon-large"></div>
    <h5>Add an event</h5>
</div>

CSS

.widgetbox {
    width: 250px;
    height: 250px;
    background-color: black;
    color: white;
    text-align: center;
}
.widgetbox [class*="icon-"] {
    display: block;
    transition-property: transform, color;
    transition-duration: 0.8s;
    -webkit-transition-property: -webkit-transform, color;
    -webkit-transition-duration: 0.8s;
    -ms-transition-property: -ms-transform, color;
    -ms-transition-duration: 0.8s;
}
.widgetbox:hover [class*="icon-"] {
	color: #24a159 !important;
    transform: rotate(360deg);
    -webkit-transform: rotate(360deg);
    -ms-transform: rotate(360deg);
}