# Additional Topics

CSS positioning can have many edge cases, especially when it comes to calculating and displaying widths of different elements. Here are some additional topics that you may want to dive into.

* [Complete guide to centering elements](https://css-tricks.com/centering-css-complete-guide/)
* [Box sizing](https://css-tricks.com/box-sizing/)
* [Flexbox, an alternative to float](https://css-tricks.com/snippets/css/a-guide-to-flexbox/)
* [CSS3 Gradients](https://css-tricks.com/css3-gradients/)
* [CSS Gradient generator](http://www.colorzilla.com/gradient-editor/)
* [CSS3 Rounded corners](http://www.css3.info/preview/rounded-border/)
* [CSS3 drop shadow generator](http://www.cssmatic.com/box-shadow)