Update to v1.0.0

I've added a new update to the script, adding background-size support and fixing a few bugs. Plus, I made numerous micro-tweaks to the JS/HTML/CSS, and a few other visible changes to the HTML/CSS, such as the addition of a GitHub banner. I've also updated the readme to reflect the 1.0.0 update. (I'm sure you can ignore the other 'merge' commits, as that was just me trying to consolidate my code branches--didn't realize I had opened so many before, haha.)