Changing embedded video's width and height

I used the video tag in my HTML5 doc to put a video on my webpage. I adjusted the width and height since the video was showing up way too big, but the controls bar was not shortened/affected by doing this so what I have is a re-sized video display screen box but an over-sized controls bar.

Here's my video tag

                <video width="50%" height="50%" controls >
                    <source src="/media/video/Monkaa.mp4" type="video/mp4">
                </video> 

So, how do I get the controls bar to adjust proportionally?