This document discusses various techniques for vertically centering content using CSS including absolute positioning, responsive designs, and percentage-based solutions. It provides examples of vertically centering content within modals, alerts and prompts using simple HTML and CSS as well as examples using Bootstrap. A percentage-based solution is presented as a newer method for vertical centering as of August 2013 that uses absolute positioning.

1. CSS Vertical Centering
https://github.com/brian-davis/encrypt-decrypt

2. • simple HTML, no styling

3. • Simple CSS styling

4. • horizontal center, no easy vertical center

5. • perfect responsive vertical centering

6. • http://codepen.io/shshaw/full/gEiDt
• http://coding.smashingmagazine.com/2013/0
8/09/absolute-horizontal-vertical-centeringcss/
• new trick as of August 2013

7. • hacking absolute positioning

8. • no style

9. • basic Bootstrap styling

10. • absolute centering

11. • perfect for custom modals, alerts, prompts

13. • modal window prompt html

14. • modal window prompt CSS & JS

15. • strong call to action
• https://ghost.org/

16. • percentage-based solution