/*.page-footer { position:absolute; bottom:0; left:0; right:0; width:100%; height:30px; }*/
.page-footer {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    height: 30px;
    background: #eee;
    z-index: 99999;
}

.footer-inner {
    padding: 0px 14px;
    display: flex;
    align-items: flex-start;
    justify-content: flex-start;
}
.footer-shell {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    transform: translateY(100%);
    opacity: 0;
    transition: transform 250ms ease-out, opacity 250ms ease-out;
    /* your background, padding, etc. */
}

    .footer-shell.footer-visible {
        transform: translateY(0);
        opacity: 1;
    }