You could add padding to the top of the element for however much you want displayed, This could then change to however much you need using javascript. If I understand correctly though, what you’re looking for is that the arrow/viewmore is always displayed. so adding a padding-top: 20px; or whatever measurement unit you like should work
I added some simple javascript here just to make it work. You probably want animations and all that…
See this jsfiddle:
http://jsfiddle.net/KPbLY/85/
To have the background not go into the padding (as mentioned in the comments) use another nested div such as:
http://jsfiddle.net/KPbLY/87/