Update prev/next card button styles: box-shadow on hover only, border-radius 5px

Agent-Logs-Url: https://github.com/ProLoser/funcheapmap/sessions/9e96c265-3137-4d8f-b42a-562ee7cb2407

Co-authored-by: ProLoser <67395+ProLoser@users.noreply.github.com>

Author: Copilot

style.css

@@ -277,6 +277,11 @@ html, body, #map-canvas {
     line-height: 1;
     padding: 2px 6px;
     min-width: 28px;
+    border-radius: 5px;
+    box-shadow: none;
+    &:hover {
+      box-shadow: 0 1px 4px -1px rgba(0, 0, 0, 0.3);
+    }
   }
 
   #event-card-counter {