add dark mode (!)

frontend/src/App.tsx

@@ -1,4 +1,5 @@
 import './App.css'
+import { ThemeProvider } from "@/components/theme-provider"
 import LatestTemperature from "@/components/latest-temperature"
 import TemperatureHistory from "@/components/temperature-history"
 import TemperaturePlot from "@/components/temperature-plot"
@@ -9,15 +10,17 @@ import TemperaturePlot from "@/components/temperature-plot"
 
 function App() {
     return (
-        <main className="min-h-screen bg-background p-6">
-            <div className="max-w-4xl mx-auto space-y-2">
-                <TemperaturePlot />
-                <div grid grid-cols-1 md:grid-cols-1 gap-6>
-                <LatestTemperature />
-                <TemperatureHistory />
+        <ThemeProvider defaultTheme="dark" storageKey="vite-ui-theme">
+            <main className="min-h-screen bg-background p-6 w-full">
+                <div className="w-full mx-auto space-y-2">
+                    <TemperaturePlot />
+                    <div className="grid grid-cols-4 gap-6">
+                        <LatestTemperature />
+                        <TemperatureHistory />
+                    </div>
                 </div>
-            </div>
-        </main>
+            </main>
+        </ThemeProvider>
     )    
 }