CSS - div height

CSS - div height

I am getting a little gap between child-div and its parent-div. Is it
possible for child-div inherit the parent-div height? or (the way
around)possible if the parent-div can scope the height of its child-div
for not to overlap or get some extra spaces.
I have a DOM like this:
<div class="parent-div">
<div class="parent-image">
</div>
<div class="child-div">
</div>
</div>