https://developer.mozilla.org/en-US/docs/Web/CSS/gradient
https://www.w3schools.com/howto/tryit.asp?filename=tryhow_js_treeview2
https://www.w3schools.com/js/js_cookies.asp
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/dialog#html-only_dialog
THREE.js 3d Packer. Array.
https://loading.io/css/