Tumblr vimeo object size trouble

i customized the vimeo video size before i embed, but still in my source code it doesn't change the exact size that i want to have. Something in my theme code maybe resize all the video's width to 250. How can i change this? Any idea?

my tumblog is: musiki.muhteviyat.com

and the problem is, i want to see full screen sign but tumblr just hides in case of width of the object.