*
{
  margin: 0;
  padding: 0;  
}
body
{
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: #000;
}
svg
{
    position: absolute;
    width: 400px;
    fill: none;
}
svg:nth-child(2)
{
    filter: blur(40px);
}
svg path
{
    d: path("M0,25 C150,110 150,-60 300,25");
    stroke: #ff0092;
    stroke-width: 50;
    stroke-linecap: round;
    transform: translate(50px,50%);
    animation: animate 2s ease-in-out infinite;
}
@keyframes animate
{
    0%
    {
        stroke: #ff0092;
        d: path("M0,25 C150,110 150,-60 300,25");
    }
    50%
    {
        stroke: #00ff00;
        d: path("M0,25 C160,-50 140,110 300,25");
    }
}