Custom font for Menu-Title and Menu-Item-Title

Site URL: http://marlin-bulldog-7lkl.squarespace.com

Hello

I have sucessfully added my custom font which is the 'Mountain Brilliant' font to the site.

@font-face {   
font-family: 'Mountain Brilliant';   
src: url(https://static1.squarespace.com/static/62fba0192a3b737239c6fc04/t/63057cfc4a7ae71eb6a2c2f1/1661304061080/Mountain+Brilliant.otf), url(https://static1.squarespace.com/static/62fba0192a3b737239c6fc04/t/63057cf35e4b432c6910d387/1661304051599/Mountain+Brilliant.woff), url(https://static1.squarespace.com/static/62fba0192a3b737239c6fc04/t/63057cf9c4469b514531358b/1661304057550/Mountain+Brilliant.woff2);}
h1 {
font-family: 'Mountain Brilliant';}
h2 {
font-family: 'Mountain Brilliant';}
h3 {
font-family: 'Mountain Brilliant';}
h4 {
font-family: 'Mountain Brilliant';}

However, in the menu page, the menu-title and menu-item-title currently assigned style are 'Heading' which still using 'Orpheus Pro' font. As far as I am concerned, the only way to change the menu-title font and menu item title font is to change the assigned style for heading. But Brilliant Mountain is not available in the font packs.  Please help me to change the Menu-Title font to the custom one. 

Use this CSS

.menu-section-title {
    font-family: 'Mountain Brilliant';
}