how to customize color of the toggle display

Rectangulum | Free Multipurpose WordPress Theme

I have a child theme and need to customize the color of the arrow in the toggle display what is the CSS for this?

I’ve tried the following, doesn’t work

a, .content-left .entry-meta p, .sticky-post-content .entry-title a, .sticky-post-content-2 .entry-title a, .widget_calendar td a, .menu-toggle::before, .toggle-top::before, .toggle-comments::after { color: #FFFFFF; }

This works, but only for the border of the toggle

a.toggle-top {
border: 2px solid #FFFFFF;

}