Do you mean the colors of the menu? I was able to change the colors of the words in the menu but was unable to change the arrows that collapse/expand… which I’m still trying to figure out.
To change the font of the menu you have to change it from your theme settings. What I did was create a child theme and add the new font info in the stylesheet of my child theme.
It really depends on your theme though. I was able to find the (.widget-area a) part under the Widgets section in my theme. It may vary from theme to theme.
This is what I have:
/* change the widget-sidebar text color to white*/
.widget-area a {
color: #fafafa;
text-decoration: none;
font-size: 22px
font-weight: 500;
line-height: 14px;
padding: 0 0px;
}