struggling with active tab text color

I have read through several strings in this forum about how to change text color in tabs, and I’ve been able to do everything that I’ve wanted/needed except for one thing–
I’d like the title in the active tab to be #8b2828, but instead it is showing dark gray.
I’ve added this text to CSS, but still no luck:
div .main_color .tabcontainer .active_tab {
color: #8b2828;
}
Can you assist?
http://familyexplorers.com – four tabs about a third of the way down the page.
Thank you,
Spencer