JAVASCRIPT COOKIES not saved

Hello
my website is at this adress:
https://licence-info.000webhostapp.com/pageJAVA.html
I’m doing a JAVA exercise for university and I wanted to save a cookie to keep page style changes from one page to another.
using this line of code in JAVASCRIPT (inserted in a more complex code):
<script>document.cookie = 'couleur=bleue';</script>
The cookie saving works perfectly fine on my computer offline.
But it doesn’t seem to work on 000webhost.
(on the page, clicking on either “sand” or “sky” option should switch page style in the whole website (using the cookie).

Are you sure cookies are enabled for that domain?

F12 -> Storage

This should show all cookies for the website you’re on