CSS text-indent too small

There is the following declaration:

.rate-thumbs-up-btn-up {
display: inline-block;
background: url(/sites/all/modules/contrib/rate/templates/thumbs-up-down/thumbs.png) no-repeat 0 0;
width: 24px;
height: 24px;
text-indent: -999px;
}

That indent is too small and you end up seeing the 'up' links on the left of the page if you have the links shown on the right of the page. Suggest changing the indent to -9999px and also for the rate down and any other similar CSS.