CheckBoxes are what they are, a box that can be checked or unchecked. In most cases, it works so developers leave it at that. But with a bit of CSS styling, CheckBoxes can look so much better. Making your forms much more appealing and effective.
However, styling CSS boxes is not as simple as styling a button or text input. Then again, it isn't that hard if you know how to work with pseudo-classes: before and after. To give you some examples of what you can do with CheckBox styling, here's some examples of the styling I used. You can use Inspect Element to see how it is done, or you can download the CSS.
Why CheckBox styling is different, not difficult
There is really not much you can do with the CheckBox itself. You can make it bigger or smaller, but that's about it. So first thing is to get rid of the CheckBox itself. Since we want to use its pseudo classes, we can not use display none. But you can set its width or height to 0.
Once the CheckBox is gone, you can use the pseudo classes and create the styling you want. Here's some examples: