ErraticFox

I'm having trouble creating a new ease or is this even possible? Example shown here: http://codepen.io/ErraticFox/pen/gMmMKX

Hello, I'm trying to add a custom bezier from here, in a example (.25,.1,.25,1), and I'm having troubles as it doesn't work. I have the element off the page with transform: translateY(-300px);, but when the animation happens, it jumps to the original position and then uses the bezier to go back up. Though I'm wanting it to start from the -300px and go down. Any help? Thanks!