All browsers require fonts to be hosted on the same domain and a subdomain is considered a separate domain name. If your font awesome icons or custom fonts are not showing up in a certain browser, below is the solution for you:
Open .htaccess file in an editor and add codes below. You can find the file in the root directory of WordPress installation.
<IfModule mod_headers.c> <FilesMatch "\.(ttf|ttc|otf|eot|woff|font.css|css)$"> Header set Access-Control-Allow-Origin "*" </FilesMatch> </IfModule>