#navbar {
    width: 100%;
    height: 50px;
}

#navbar:not([loaded]) {
    --dark: #141414;
    --light: rgb(102, 102, 102);
    background-image: linear-gradient(to right, var(--dark) 30%, var(--light), var(--dark));
    background-size: 200% 100%;
    background-repeat: repeat;
    background-position-x: 0%;
    animation: navbar-animation .75s linear infinite;
}

#navbar[fixed] {
    position: fixed;
    top: 0;
    left: 0;
}

@keyframes navbar-animation {
    0% {
        background-position-x: 0%;
    }
    100% {
        background-position-x: 200%;
    }
}