Creating a Rollover - my form blows out

I'm trying to create a rollover effect for the submit form. I have it working but its not positioned correctly AND the rest of my form blows out.

I created a class for the button image:
body #gform_wrapper_1 .gform_footer input.button {text-indent:-9000px}

.submit1 {
background: url(http://www.tacoburritoking.com/site/wp-content/uploads/2012/03/Buttons.jpg) no-repeat;
border: none;
cursor: pointer;
width: 50px;
height: 20px;
}

.submit1:hover {
background-position:-52px 0;
}

So instead of my button showing up on the bottom of the form its all the way on top

Ah... Thanks for reply I fixed it using the info here: http://www.gravityhelp.com/forums/topic/css-for-newbies-or-rusty-coders