style.css

*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body{
    font-family: 'Poppins', sans-serif;
    background: #18191f;
}

.container{
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 10rem;
}

#twitter,
#github,
#facebook,
#youtube{
   font-size: 8rem;
   background-color: #18191f;
   color: #fff;
   box-shadow: 2px 2px 2px #00000080, 10px 1px 12px #00000080,
   inset 2px 2px 2px 10px #00000080,
   inset 2px 2px 10px #00000080,
   inset 2px 2px 10px #00000080;
   border-radius: 1.8rem;
   padding: 1rem 1.3rem;
   margin:1rem;
   animation: animate 3s linear infinite;
   text-shadow: 0 0 50px #0072ff, 0 0 100px #0072ff, 0 0 150px #0072ff, 0 0 200px #0072ff;
}

#github{
    animation-delay: 0.3s;
}
#facebook{
    animation-delay: 0.7s;
}
#youtube{
    animation-delay: 1s;
}

@keyframes animate {
    from{
        filter: hue-rotate(0deg);
    }
    to{
        filter: hue-rotate(360deg);
    }
}