Fix grid UI on mobile

src/app/calendarOverviewCard.tsx

@@ -88,5 +88,4 @@ export function CalendarOverviewCard() {
             }}
         />
     </Card>
-
 }

src/app/page.tsx

@@ -6,7 +6,7 @@ export default function Home() {
         <main className="m-6">
             <h1 className="text-3xl font-semibold text-slate-900 dark:text-white my-2">Revision Tracker</h1>
 
-            <div className="grid gap-5 grid-cols-4">
+            <div className="grid gap-5 grid-cols-1 sm:grid-cols-4">
                 <SubjectOverviewCard
                     projectId={195482340}
                 />