PWA chrome: manifest theme_color #009688 teal -> cream #faf8f5, background black -> cream; index.html theme-color light/dark pair; html/body bg matches theme (fixes green top bar + white bottom bar in Firefox PWA)

assets/custom.css

@@ -119,3 +119,8 @@ footer a {
 footer a:hover {
   text-decoration: underline;
 }
+
+/* Bare page background: cream in light, deep pine in dark — so any viewport
+   area the app UI does not cover (e.g. PWA navigation-bar insets) matches. */
+html:not(.dark), html:not(.dark) body { background-color: rgb(250, 248, 245); }
+html.dark, html.dark body { background-color: rgb(34, 39, 31); }