https://codemyui.com/scroll-up-to-reveal-header-and-scroll-down-to-hide/
No-Library (pure JS), HTML, CSS, JavaScript
https://css-tricks.com/css-scrollbar-with-progress-meter/
https://codepen.io/RadDog25/pen/RwPjBag
https://css-tricks.com/sticky-table-of-contents-with-scrolling-active-states/
https://css-tricks.com/examples/hrs/
jQuery 3.2.1, HTML, CSS, JavaScript
https://codepen.io/see8ch/pen/fLxuK
https://freefrontend.com/css-text-shadow-effects/