jsFiddle is the perfect solution; it provides a custom environment (based on user selections) to test (or fiddle with) your JavaScript, HTML, and CSS code ... The following list provides a sample ...

But you don’t need to use it, and your sites can still look good without it. How Do CSS and HTML Work Together? If you ...

As the available computing power from affordable microcontrollers continues to increase, there is an inevitable blurring of the line between them and the lower tier of application processors ...