JQuery :: Animate With A Percentage Placed Div?

I have divs on a page that are placed in the center with something like
width:100px;height:100px;position:fixed;top:50%;left:50%;margin:-50px, 0, 0, -50px;
I want to animate this div to the bottom left (similar tominimizingeffect on windows)

I am trying to use.animate({

opacity: 0.25,

left: '10px',
bottom: '10px';
height: 'toggle'
}, 5000);

However when I activate this it simply jumps (or glitches) to that position, the opacity and height animate perfectly.