Class stopped working on Learn HTML & CSS

I’m in the middle of a task on “Learn HTML & CSS” I’m in the task ‘THE CSS SETUP
Linking the CSS File’
when I click RUN the page just loads and nothing happenes
Nothing changes even when I click Back or Next
Just ‘http://localhost:8000’ trying to load…
Please help I can’t continue from here and I love this class

Please present the code you are using
the link to the exercise…