Why does my CSS code change when transferring to HTML product link?

Hello, I’m new to coding and wanted to give it a try! I’m adding a button to my product page but when I make test the code on https://www.w3schools.com/ and transfer it to my HTML product link it changes the code.

Example:

Client Services
Enquire A Studio Visit 〉

Changes to

Client Services
Enquire A Studio Visit 〉

Would love to know why! Thank you!

What is the element you’re adding? Are you hoping to bold the text?

I would suspect the html validator is asking something similar to me and trying to make your code valid.