Change headings font

Hello everyone,

I am trying to change font of headings. I created child theme for that and defined my custom font. But the change is not shown in the final site, because it gets overwritten by the customizations in themes Design/Typography section.

So I have something like this included in final html:

<style type="text/css">#page:before, .sidebar-offcanvas, #secondary { background-color: #333333; }@media (max-width: 1199px) { #page > .container { background-color: #333333; } }</style><style type="text/css">#masthead .site-title {font-family:Amatic SC}body {font-family:Roboto }h1,h2,h3,h4,h5,h6 {font-family:Roboto Slab}#masthead .site-description, .hentry .entry-meta {font-family:Roboto Condensed}</style>

This makes my changes in style.css overriden.

Is there a sane way I can disable these customizations in my child theme?

I have seen require get_template_directory() . '/inc/customize.php'; # Enables user customization via admin panel in parent theme, but I have no idea how to override this in my child theme.

I am looking forward for some robust solution to disable these design customizations together (because I will probably try to make more design changes), so I can define ALL changes in my style.css and in my style.css only (= no settings in wp-admin possible).

Any pointing to correct direction is very appreciated.

PS: I can not provide live link to the site right now.

Thank you