I haven't used it but the page says "it collapses the Google left sidebar by default with the option to expand". This script was also updated 10 hrs ago, "you'll see this right next to the authors name" , so it's a new script just for what you would like done.
Tends to look like your idea is now fucked by google
You could always install Stylish and then download one of the tons of google styles. Like you guessed it is just a program that uses custom CSS files for your browser. You can use either global styles or particular site styles like Google or Facebook or you can make your own.