Comment by hyperknot

Add this to fix the contrast in all your dark themes:

  "experimental.theme_overrides": {
    "background": "#111",
    "panel.background": "#111",
    "text": "#eee",
    "text.muted": "#ccc",
    "title_bar.background": "#111",
    "tab_bar.background": "#111",
    "toolbar.background": "#111",
    "status_bar.background": "#111",
    "element.selected": "#333",
    "editor.background": "#000",
    "editor.gutter.background": "#000"
  }