yvonne.r on "WP eStore - Customizing the buttons (changing the button images)"

Hi, I tried to customize the subscribe button using CSS as described here but it didn't work.
What I did: I entered the following code into "wp_eStore_custom_style.css"

.eStore_subscribe_button{
border: 1px solid #B3B3B3;
background: #ffc60b;
}

And I am using this code to add the button on the site: [wp_eStore_subscribe_button id="1"]

Could you please help?
Thank you.