wayvr/dash-frontend/assets/gui/theme.xml

<layout>
  <theme>
    <var key="color_menu_dark" value="#0A0A0ACC" />
    <var key="color_accent" value="#008cff" />
    <var key="color_top_panel" value="#00000099" />
    <var key="color_bottom_panel" value="#141e28" />
  </theme>
</layout>