Change colour of orange slider under navigation?

Can you link to a Webpage with the orange slider?

https://www.revitalisecollagen.co.uk
just under the navigation bar items, where the currently active item is shown
Thanks for your help

If you’re not using a Child Theme, and if the theme doesn’t have a designated section of the dashboard for CSS modifications then install this Custom CSS Manager plugin https://www.ads-software.com/plugins/custom-css-manager-plugin

Then use its “CSS Code” section of the dashboard to hold your CSS modifications:

Alternatively use your Child Theme style.css file to hold your CSS modifications:

#et_active_menu_item {
    background: red;
}

https://www.w3schools.com/html/html_colornames.asp

Thanks Andrew – I’ve made your suggested change in a child theme, but no luck! I changed #et_active_menu_item as suggested, but the bar still shows orange.
I know my child theme is working. Even changing #et_active_menu_item in the main theme CSS has no effect.
Any other ideas?

Try:

body #et_active_menu_item {
    background: red;
}

Thanks Andrew – that worked! ??