Backup document root and MySQL in Linux
Since you are repeatedly using $(date +\%F-\%T), you can store that as a variable (unless you want to also know how long it took the script to jump between statements). Use that variable instead.

Similarly, set a basepath, which in your case, is /var/www/html. In case it changes in the future, it'll be just enough to change it in one place.

At the end, you have

rm -rf db-$(date +\%F-\%T).zip html-$(date +\%F-\%T).zip


which will try to delete those files from CWD, which might not be the same as /var/www/html.

mysqldump has options such as --compact and --compress. Making use of them will result in smaller sql files, resulting in even smaller zips; saving you some disk space.