As you can see, via template overrides, you can pretty much define any CSS
classes you want. For those of you who are into creating and tweaking template overrides, unless you're going to create a highly custom, private, not-for-the-public template, my recommendation is you continue to use Joomla's general CSS
classes for component and module output as much as possible.
This is a good way to ensure your template is familiar to other Joomla! administrators, especially if you want to offer your template to the public or for commercial sale. It's easy for them to look up and customize CSS rules rather than forcing them to discover all the new and interestingly-named CSS
classes you created. For those of us ...