Code in the body is not responsive

Hello, I’ve added the following code to the body section:

<div class=”alertbar”>Check out the Java Developer Roadmap and get your dream job! 🠖 HERE!</div>

But, on a mobile device, it looks like this: https://i.postimg.cc/C11kyjSf/wordpress-issue.jpg

The same if I put it into the header section.

Can you help me fix this?

Thanks