Communicate, don’t decorate.
The sooner you learn to communicate with your designs using only what’s necessary and relevant, rather than decorate for the mere purpose of decorating, the sooner you’ll find your designs touch the consumer’s heart, rather than just satisfy the designer’s eye.
When debugging your CSS, strip down to the base element (div, p, etc) and work up. I’ve found it extremely useful over the course of my career to comment out everything except the element that you think is the cause of the problem. Once I’m positive that element displays properly (or isn’t the problem), I uncomment in the next containing element. Once that element is working properly in tandem with the previous element, I uncomment the next element. And so on. A simple technique, no doubt, but often a useful one.