Working with CSS in Moodle is more complex than with a content management system such as WordPress. This post describes two simple ways to add new custom CSS styles to the default Boost theme in Moodle 3.3, such as custom table styling. It does not cover tweaking existing theme CSS.
Learning Management Systems (LMS) like Moodle are all the rage these days in higher education course delivery. While an LMS almost certainly simplifies the day-to-day administrative tasks involved in higher education, it does not necessarily deliver better pedagogy or a better educational experience for students.