questions are as follows:
:
:
you can see that the same content area becomes 0
maybe that"s why.
but why did the content area become 0?
about absolute positioning
position:absolute is relative to the first parent element in its containing block that has a position:absolute or position:relative attribute, if none, relative to body.There"s no problem with
. The parent container of content is position:absolute, and the parent container has width and height in the switching process. Otherwise, body is also located by relative. How can a height of 0 occur?