*Learn CSS Layout Step by Step:* http://learnlayout.com/no-layout.html
*All About Floats:* https://css-tricks.com/all-about-floats/
*CSS sample -- how to clear floats:* https://snippets.cacher.io/snippet/ebae00d03f900cceb413
*Positioning Content* (info on floats, inline-block, and relative & absolute positioning): https://learn.shayhowe.com/html-css/positioning-content/
*`{ box-sizing: border-box }` -- an alternative for (sometimes) easier layouts:* http://blog.teamtreehouse.com/box-sizing-secret-simple-css-layouts
*Progressively Enhancing CSS Layout: From Floats To Flexbox To Grid:* https://www.smashingmagazine.com/2017/07/enhancing-css-layout-floats-flexbox-grid/
*Kill zombies AND learn Flexbox* (a goofy, free, gameified way to learn advanced layouts): https://flexboxzombies.com/p/flexbox-zombies
*Learn CSS Grid in 5 Minutes:* https://medium.freecodecamp.org/learn-css-grid-in-5-minutes-f582e87b1228