How do I change the font?

Developer help
1

I’m using the “Casper” theme. I want to set the font of the text caption to “Poppins”. I want to make category titles “Monsterrat” but I don’t know how to do that.

2

At first add the fonts in default.hbs file
Example :

<link href="https://fonts.googleapis.com/css?family=Montserrat:400,700|Poppins:400,700" rel="stylesheet">

and then use the following css in Code injection area

Example :

<style>
span.post-card-tags {
 font-family: Monsterrat, sans-serif;
}
</style>