Add scrolling to #proof-tree-container for overflow content

- Updated #proof-tree-container CSS to enable horizontal and vertical scrolling when content overflows.
- Ensured the #proof-tree remains centered within the container.

src/App.vue

@@ -200,9 +200,13 @@ export default {
   display: flex;
   justify-content: center;
   align-items: center;
-  min-height: 400px;
+  min-height: 700px;
   border: 1px solid #dcdfe6;
   padding: 20px;
+  overflow: auto;
+  /* Enable scrolling */
+  box-sizing: border-box;
+  /* Ensure padding is included in the width and height */
 }
 
 #proof-tree {