Wanting to use flexbox, I thought this idea would make a good first project. I've organised the blocks into the reasonable size and shape and it works on a good variety of different sizes and shapes of screens.
This is also the first time I've tried to connect javascript to an html file, and there were a few headaches. I couldn't get a while loop to run to continually update the background colours of the divs, so I had to keep reloading the page instead. This, I think is causing the screen to flash every 4 seconds.
Overall pretty pleased with this as it's a project I started myself and didn't follow a tutorial at any point.