Input[type="image"] won't budge

I tried to make the button go down with margin, padding, top to be on the same level as other input and label, but it won't budge.

html code: see image

   input[type="image"] .button-update-cart{
top:100px;
}

On the form, image is out of the place for example: see this image

EDIT

.page-cart .cart-totals .promo-code .field .button-update-cart{
position:relative;
}

.page-cart .cart-totals .promo-code .field input[type="image"]
{
top:100px;

}

it doesnt w开发者_C百科ork :(

Any insight will be appreciated!

---

You need to give the element position: relative to have the top have any effect.