* flex box for photos:
https://coryrylan.com/blog/css-gap-space-with-flexbox
https://www.developerdrive.com/responsive-image-gallery-flexbox/
* display pop up modal when click on image:
https://stackoverflow.com/questions/61986259/display-popup-by-clicking-image-for-multiple-image
https://dzone.com/articles/4-ways-to-create-a-modal-popup-box-with-html-css-a
* .draggable() & .append() with jquery:
https://jqueryui.com/draggable/
https://api.jquery.com/append/
*turn background into p5.js sketch:
https://www.youtube.com/watch?v=OIfEHD3KqCg