CSS code to achieve Absolute center of Div Layer

There is a saying that good, table can do the effect, div omnipotent, on the contrary, not unexpectedly. Horizontally centered, with CSS set very simple, vertically centered, sometimes baffled some people. In the previous project did not encounter the vertical center of the example, also did not go too much research, recent leisure, made a percentage of high, vertical, horizontal center. This can extrapolate. The percentage is OK, the fixed size is simple.

[Ctrl + A ALL SELECT hint: You can modify some of the code, and then run]