HTML/CSS IDs and Classes Course Error?

Question

On course https://www.sololearn.com/learn/CSS/1080/, (the 3rd article) the following is said:

"Class selectors work in a similar way. The major difference is that IDs can only be applied once per page, while classes can be used as many times on a page as needed."

However, with my code, I used the id multiple times.
https://code.sololearn.com/Wc6qmEabiV3P/?ref=app

And it works. Is there an error in the tutorial?

Can someone please explain what they mean by "...IDs can only be applied once..."

Answer 1

No error in tutorial

The reason of using id will be understood only if you know about javascript.

In js if you need to get the value of the element or need to change the value of the element, ID is used!

CSS may work with multiple ones, but incase of js you will get an error..,,
'If you still struggling with this, just mention my name in the comment section, I'll elaborate with sample code

Happy to help you