height: auto, automatic height adjustment means according to the content of the blocks.
height: 100%, the height refers to the height relative to the parent block defined, i.e. according to the height from its parent layer and has recently defined a height of defined height.
Browser is how to calculate the height and width?
width
Web browser when calculating the effective width will consider the width of the browser window open. If you do not set any default value for the width of the browser that will automatically fill the entire page content tiled lateral width.
Height () Special
Browser did not calculate the height of the content, unless the content exceeds the window range (resulting in a scroll bar appears). Or you set up a whole page to the absolute height. Otherwise, the browser will simply let down the contents of a pile, height of the page is simply no need to consider.