button.btn_glow {
    clear: right;
    right: 0;
    height: 60px;
    width: 200px;
    margin: 18px 35px;
    font-size: 20px;
    font-weight: bolder;
    letter-spacing: 2px;

    position: relative;
    border-radius: 50px;
    border: none;
    outline: none;
    background: #111;
    color: #fff;
    text-transform: uppercase;
    cursor: pointer;
    transition: background 0.5s;

    z-index: 1;
    animation: glow 14s linear infinite;
    background: linear-gradient(90deg, #03a9f4, #f441a5, #ffeb3b, #03a9f4);
    background-size: 400%;
}
@media (max-width: 768px) {
    body {
        min-width: 415px;
    }
    button.btn_glow {
        float: right;
        right: 80px;
        height: 50px;
        width: 150px;
        margin: 18px 15px;
        font-size: 16px;
        letter-spacing: 0px;
    }
}
button.btn_glow:hover:before {
    opacity: 1;
    z-index: -1;
}
button.btn_glow:hover{
    z-index: 1;
    animation: none;
    background: #006b08;
}
@keyframes glow {
    0%{
        background-position: 400%;
    }
    100%{
        background-position: 0%;
    }
}