/* Option 1: prefix on the <code> element */
code.xref.py.py-dec::before {
  content: "@";
  margin-right: .1em;
}

/* Option 2: prefix on the inner <span> */
/*
code.xref.py.py-dec > span.pre::before {
  content: "@";
  margin-right: .1em;
}
&/

/* Optional: make decorators pop a bit */
code.xref.py.py-dec {
  font-weight: 600;
}