Improve container responsiveness for mobile

- Adjust width to 90% with max-width of 600px
- Replace fixed pixel padding with relative units
- Modify margin for better spacing on smaller screens

muninn.css

@@ -32,11 +32,12 @@ body {
     text-align: center;
     display: flex;
     flex-direction: column;
-    padding: 20px 20px 40px 20px;
-    margin: 36px auto;
+    padding: 1.25rem;
+    margin: 2.25rem auto;
     background-image: url(../HavamalStanzas/vellum-75.png);
     border-radius: 8px;
-    width: 50%;
+    width: 90%;
+    max-width: 600px;
     min-height: 150px;
     box-shadow: 0 0 10px rgba(0, 0, 0, 0.5);
 }