Expert hierarchy as a self-contained native-HTML tree (collapsible <details>, in-page filter, zero JS dependencies) replacing the networkD3 widget, which rendered with broken layout when saved standalone. resy_expert_tree(fill=TRUE) reconstructs the implied group levels (Q11 -> Q1 -> Q) with the expert file as the authority: synthesised single-child wrappers it does not define are collapsed, so EUNIS-ESy roots at MA (not an invented M). Cross-checked vs EUNIS 2021/2022 online. --as-cran 0/0/0.