Small window in the upload file area of a link

when i try to upload a file for a product from the link a get a very small window and i cant find the file that i upload i can see the that the height is 40:px element{
height: 40 px; }
but i cant find it nowhere
can you please help me to fix it
i noticed that is a general problem i try it in the demo page of opencart and the same thing happens