why css transform of button is capturing its old space

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CSS3

I have a button in a div.When the button is rotated -90deg the button becomes vertical but the div is not decreasing and there is empty space as the button became horizontal to vertical.
When I use this thing in my project,the div is capturing its space.I attached the whole thing in right side of window like feedback button you can see in all projects.But the textboxes which are near the div can not take focus due to the region is captured by div space.
So to get the focus on textboxes I have to keep those by leaving a space which is equal to the div's width,but the empty space destroying the look.

So how to implement it?