Form Submit Button Press

[Clint Malarchuk]

hi. I am working on CSS forms and have chosen an image for my submit button. I have created a darker version of the image for when the user has clicked down on the submit image button. How can I apply it so that while the user is clicking the button the second darker image is present?

[Coyotelab]

.button {background: url(img-location) no-repeat; width: 100px; height: 30 px; ...}
.button:active {background: url(img-location-active) no-repeat; width 100px; height: 30px; ...}