How to remove span when burger menu is open?

Question

css

How to remove span when burger menu is open?
span.is-open::after {
display: none
opacity: 0;
}
It doesn't work, I don't know how to overcome this problem

Answer 1

span.is-open::after {
display: none;
opacity: 0;
}

The semicolon is missing, mb.
Well, more information is needed. HTML and CSS.