Hi ORE,
You are right. Sorry, about that. I missed to add that 2 more files are required.

   <link rel="stylesheet" type="text/css" href="../../../source/styles/components/smart.base.css" />
    <link rel="stylesheet" type="text/css" href="../../../source/styles/components/smart.tabs.css" />
    <link rel="stylesheet" type="text/css" href="../../../source/styles/components/smart.common.css" />

When you use more components on the page and want to load only these styles, add them between smart.base.css and smart.common.css.
Best regards,
Peter Stoev
Smart UI Team
https://www.htmlelements.com/