full width gif image

i am new so sorry to ask something like this but i try to post full width gif image but its not working :O i use this code

<img class=" alignleft" src="http://p.fod4.com/p/media/d153865d63/8cdIekLRSS6iqxDGhgQH_Laser%20Shorts.gif" alt="" width="100%" />

any one can help me?

site http://laughinghive.com/entertainment/10-gifs-of-pet-owners-trolling-their-dumb-animal-friends/