Timeline Arrow color

Hi, I’ve only started using the theme with 3 days support left. Can you please tell me how to change the color of the timeline arrows when viewing on a mobile device. I only have 3 timeline entries therefore the arrows don’t show on desktop but on mobile they are a very light grey color.

I have tried this code but it makes no difference :

.main_color .av-timeline-nav a span {
background-color: #ff7827;
opacity:1;
}

There is a holding page on site right now therefore I have provided sign in details.

thanks