Section XVIII: absolute center

Common programming problem: Do vertical and centered text: text-align: center with the line-height (or a simple text characters within the line block may be experts level to the external box line-height)

                        Centered around the vertical image want: text-align: center with the vertical-align: middle (row simple picture or image block within expert)

                       Want the image vertically and horizontally centered: If the text images encased within a seat body level block-level box: An absolute positioning or using the dummy elements.

               利用伪元素：:before（display:inline-block content:""  vertical-align:middle  width:0 height:100% )

                                              Or: height: 50%, do not give a vertical-align: middle 

                                                        height: 100% necessary vertical-align: middle

                                                                   

                      Absolute positioning center: absolute block-level centered want: 1 using position (Location)

                                                  Absolute Center: The first recommendation :()

                                                The second (I do not know absolutely centered in the width and height of the case):