z-index grief

[Sir Osis of Liver]

Working with Nightbreeze 2.0 responsive theme, having a problem with dropmenu opening behind other elements in mobile view.  If responsive.css is loaded I get this in mobile view -

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If I disable it, dropmenu opens on top -

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In pc view it opens on top either way.  Inspector is not showing me anything from responsive.css for dropmenu or elements below.  Changing z-index has no effect.  Not sure what to look for.