Height doesn't work well in IE

HTML & CSS
1

I tested my page in FF, Chrome,…it works very good. But when I checking (using IE9), the height of search form doesn’t full of parent height. Hope someone help me. Thank in advance.

Here is my code:

http://codepen.io/thehung1724/pen/kCDEf
2

Looks fine to me in IE9. :-/

3

You don’t understand my question clearly, so please take a look at image below.