Change accordian ‘X’ icon

Hello –
Thanks for a great theme.

I have a quick question about swapping out the “hb-moon-close-5” that is used in the FAQ’s .hb-accordion-tab i, for “icon-ok-circle” without making a mess of things. What CSS or approach would you suggest?

I tried using this CSS but was unsuccessful:

.hb-accordion-tab i.hb-moon-plus-circle:before {
display: inline-block;
font: 14px/1 FontAwesome;
font-size: inherit;
text-rendering: auto;
-webkit-font-smoothing: antialiased;
content:”\f05d”;
}

Thank you for your time.