function slider_slide(slider, d) {
    let slider_obj = o(slider);
    let left = slider_obj.style.left;
    let left_px = Number(left.substr(0, left.length - 2));
    left_px += d;
    slider_obj.style.left = left_px + "px";
}

function reset_slider(slider) {
    o(slider).style.left = "0px";
}