commented "main" stop extension

[hugo-levet]

My code with commented "main" is stopping

This code works:

div {
    background: red;
}

This code does not work:

// main
div {
    background: red;
}

Why it's not work? It's a bug or it's a normal?

[sibiraj-s]

Hi, Formatting works fine for me. Do you see any errors in the output?