Teascade.net/src/resources/css/loadbar.css

#loadbar {
    position: absolute;
    top: 0;
    left: 0;
    height: 0.2em;
    background-color: var(--highlight-color);
    z-index: 1;
    transition: 0.1s;

    width: 0%;
    opacity: 0;
}

#loadbar.loading {
    opacity: 1;
}