.custom-controls .text-muted {
    color: #ffffff !important;
    background-color: red;
    max-width: fit-content;
    padding: 5px 15px !important; 
    border-radius: 5px!important; 
    background-color: black;
    -webkit-animation: blink 800ms step-end infinite;
            animation: blink 800ms step-end infinite;
}
@-webkit-keyframes blink { 50% { background-color: black; }}
        @keyframes blink { 50% { background-color: red; }}