Overiding WooCommerce CSS

Hey, I’m trying to change the background colour and text colour of a specific tab when selected. The CSS is the correct selector from what I can see in firebug but the colours wont change?

.simfree-plans_tab .active > a {
    background: #52b9e9 none repeat scroll 0 0 !important;
    color: white !important;
}

https://ww.wp.xz.cn/plugins/woocommerce/