app/static/loader.css

.loader{
    width: 100%;
    height:20px;
    background: white;
    /* -webkit-box-reflect: below 1px linear-gradient(transparent,#0005); */
    position: absolute;
    top: 0;
    border-radius: 50px;
    overflow: hidden;
    z-index: 23;
}

.loader::before{
    content:"";
    position:absolute;
    inset:0;
    background: linear-gradient(90deg,#fb0094,#0000ff,#00ff00,#ffff00,#fb0094,#0000ff,#00ff00,#ffff00,#fb0094);
    animation:loader_animate 20s linear infinite;
    background-size:500%;

}

@keyframes loader_animate {
    0%{
        background-position: 0 0;
    }
    0%{
        background-position: 500% 0;
    }
    
}

.loader.hidden{
    display: none;
    
}

#loader_text{
    margin: 0px;
    z-index: 24;
    position: absolute;
    left:50%;
    transform:translate(-50%,0);
    background: transparent;
}