Clay was working on the website today. He must have changed the background colors of several CSS containers to see where they were, and then forgot to change them back. He fixed it earlier, but some people were still seeing the messed-up parts because their browsers were remembering it. Browsers will remember what pages look like (images, backgrounds, etc) so when you visit those pages again, the browser can load them quicker. Hitting refresh tells your browser to forget what it knew the website looked like earlier, and reload everything on the page “from scratch”.