CSS: Position Introduction.
①absolute locate:http://www.runoob.com/try/try.php?filename=trycss_position_absolute
②fixed locate:http://www.runoob.com/try/try.php?filename=trycss_position_fixed
③relative locate:http://www.runoob.com/try/try.php?filename=trycss_position_relative
http://www.runoob.com/try/try.php?filename=trycss_position_relative2
④static locate:http://www.runoob.com/try/try.php?filename=trycss_position_static
⑤sticky locate:http://www.runoob.com/try/try.php?filename=trycss_position_sticky
⑥inherit locate:继承
⑦initial locate:初始化为默认值
# Overlapping elements(重叠的元素)using z-index to solute:http://www.runoob.com/try/try.php?filename=trycss_zindex