How to style HTML5 <meter> tag

meter::-webkit-meter-bar {
    background: #FFF;
}
meter::-webkit-meter-optimum-value {
    background: linear-gradient(to bottom, #62c462, #51a351);
}
meter::-webkit-meter-suboptimum-value {
    background: linear-gradient(to bottom, #fbb450, #f89406);
}
meter::-webkit-meter-even-less-good-value {
    background: linear-gradient(to bottom, #ee5f5b, #bd362f);
}