Use lato as default font for headers too

frontend/src/assets/scss/variables.scss

@@ -1,6 +1,5 @@
-
 $font--role-default: 'Lato', sans-serif;
-$font--role-emphasis: 'Montserrat', sans-serif;
+$font--role-emphasis: 'Lato', sans-serif;
 
 $color__text--primary: rgba(0, 0, 0, 0.87);
 $color__text--secondary: rgba(0, 0, 0, 0.54);