// ==UserScript==
// @name        O'Reilly Helper
// @namespace   https://github.com/mefengl
// @version     0.2.0
// @description 🎴 Enhance your O'Reilly learning experience: smoothly hide header and footer on scroll down, and show them (with cute transparency!) on scroll up.
// @author      mefengl
// @match       https://learning.oreilly.com/library/view/*
// @icon        https://www.google.com/s2/favicons?sz=64&domain=oreilly.com
// @license     MIT
// @grant       GM_addStyle
// ==/UserScript==
(function () {
'use strict';
GM_addStyle(`
header, #content-navigation {
transition: opacity 0.5s linear;
}
`);
let lastScrollTop = window.pageYOffset || document.documentElement.scrollTop;
let isScrollingDown = false;
let header = document.querySelector('header');
let footer = document.querySelector('#content-navigation');
if (header) {
header.style.opacity = '0.6';
header.style.transition = 'opacity 0.5s';
}
if (footer) {
footer.style.opacity = '0';
footer.style.transition = 'opacity 0.5s';
}
window.addEventListener('scroll', function () {
let scrollTop = window.pageYOffset || document.documentElement.scrollTop;
if (scrollTop > lastScrollTop && !isScrollingDown) {
isScrollingDown = true;
// On scroll down, hide header and footer
if (header) header.style.opacity = '0';
if (footer) footer.style.opacity = '0';
} else if (scrollTop < lastScrollTop && isScrollingDown) {
isScrollingDown = false;
// On scroll up, show header and footer
if (header) header.style.opacity = '0.6';
if (footer) footer.style.opacity = '0.6';
}
lastScrollTop = scrollTop <= 0 ? 0 : scrollTop; // For mobile
}, false);
})();