/* Force the Back label to be visible, even in no text */
toolbar:not([mode=full]) #back-button .toolbarbutton-text {
display: -moz-box !important;
}
/* Put the Back label to the right of the button */
toolbar:not([mode=full]) #back-button .toolbarbutton-menubutton-button {
-moz-box-orient: horizontal !important;
}
/* Put some spacing around the Back button icon */
toolbar:not([mode=full]) #back-button .toolbarbutton-icon {
margin-left: 8px;
margin-right: 8px;
}
/* Remove Forward button when there's nothing to go forward to */
#forward-button[disabled="true"] { display: none; }
For Firefox 1.0, just replace 'margin-' with 'padding-'.