What is deadlock all about

Answer 1

"html" isn't something I'd normally associate with "deadlock" so...more details are needed I think.

To help others answer, what's the context?

Answer 2

If we have two or more threads of execution, and first thread whant some resource, that second holds, and second thread whant another resource, holded by first one.
But this situation can only be in multythreading system. HTML isn't about this.