Class doesn't work

When I give Class=“text-center” to my <h1>,it doesn’t work!
And I don’t know what the problem is,what should I do?

Are you using Bootstrap? If so, have you loaded Bootstrap into your project? :slight_smile:

Please post a link to your code if available, so that people don’t have to guess and suggest solutions that may not be useful.

I have solved this by adding the Bootstrap ,thank you