Stuck with HTML+CSS vertical format

Stuck with HTML+CSS vertical format
0
#1

Hi All, my first post here and I have developed a couple of android apps before and moving into a totally new territory of web development. I am having some trouble with filling in the screen vertically.
Here’s the link: h t t p s : / / r e a c t s a m p l e - b 1 a 7 a . f i r e b a s e a p p . c o m

I am trying to fill the orange div section to 50% of the screen and the rest with equal height, filling the screen.