Grabbed dndbeyond's source code

```
~/go/bin/sourcemapper -output ddb -jsurl https://media.dndbeyond.com/character-app/static/js/main.90aa78c5.js
```

ddb_main/theme/index.ts

@@ -0,0 +1,29 @@
+import {
+  createLightTheme,
+  createDarkTheme,
+} from "@dndbeyond/ttui/mui/theme/createTheme";
+
+type PaletteOpt = "light" | "dark";
+
+export const getTheme = (lightOrDark: PaletteOpt = "light", primary?) => {
+  const primaryOverride = primary ? { primary: { main: primary } } : null;
+  const themeOverrides = {
+    palette: primaryOverride ?? {},
+    zIndex: { modal: 99999 },
+    components: {
+      MuiPaper: {
+        styleOverrides: {
+          root: {
+            backgroundImage: "none",
+          },
+        },
+      },
+    },
+  };
+
+  if (lightOrDark === "light") {
+    return createLightTheme(themeOverrides);
+  } else {
+    return createDarkTheme(themeOverrides);
+  }
+};