As this answer explains, if there are no (top, left, right, bottom) position attributes: the absolute element will be placed by default, as if it were part of a normal flow
, this is useful if you want to maintain a position: absolute next to her sibling, like a tool tip, and manipulate it using the margin property, say:
margin-top:-40px; margin-left:30px;

but if you set any (top, left, right, bottom), it will reset by default and will refer to the parent.
top:0

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