.mejs__loop-button > button,
.mejs-loop-button > button {
    background: url('loop.svg') no-repeat transparent;
}
.mejs__loop-off > button,
.mejs-loop-off > button {
    background-position: -20px 1px;
}

.mejs__loop-on > button,
.mejs-loop-on > button {
    background-position: 0 1px;
}