Solved How can I style variables?

I use variables on my site so that, for example, the telephone number is in a uniform format everywhere.
Currently I use code snippets that I include in the functions.php file. Is there a way to style them and, for example, give them an individual color or change the size?


The code:
function telefon_shortcode() {
$telefonnummer = get_theme_mod('meine_telefonnummer', 'Standard Telefonnummer');
return "<p>+49 911 977 912 40</p>";
}
add_shortcode('telefon', 'telefon_shortcode');

I would be pleased to receive an answer.