I have a checkbox and a Label to style, depending whether the checkbox is checked. So far I used the [selectivizr] script 1 to manage :selected propperty workin
:selected
Your hex values are wrong for the IE6-9 part:
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#00bf00', endColorstr='#009400',GradientType=0 ); /* IE6-9 */