Ohh, i understand what you mean.
Before using the "Open Sans" or "Oswald", you should first load them. You can use Arial, Times, Verdana etc.. without loading them, because all computers have those font-families pre-installed.
But Oswald, Open Sans, Roboto etc.. they are special font-families and you should load them first on the page. They are usable in the website on normal pages, but "Pop-ups" are different, they are like "Pages without the Joomla Wrap"
So, in the
/templates/flexible_coolmart/component.php file, right after the
<head> tag, include these lines below to load those font-families...
for, Opens Sans
<link href='https://fonts.googleapis.com/css?family=Open+Sans' rel='stylesheet' type='text/css'>
for, Oswald
<link href='https://fonts.googleapis.com/css?family=Oswald' rel='stylesheet' type='text/css'>
Browse
www.google.com/fonts for all other font-types.
then, within the "custom.css" you can use those font-families as follow:
.contentpane h1 {font-family: 'Open Sans'; font-weight: 300;}
.contentpane h1 {font-family: 'Oswald'; font-weight: 400;}
and they will be effective on popup as well:
Regards.