fix: enforce mobile 1-col layout and prevent horizontal blowout

client/src/index.css

@@ -80,6 +80,8 @@ body {
   display: flex;
   flex-direction: column;
   min-height: 100vh;
+  width: 100%;
+  overflow-x: hidden;
 }
 
 /* Header */
@@ -517,8 +519,11 @@ body {
 }
 
 @media (max-width: 992px) {
-  .grid-2col, .grid-equal-2col {
-    grid-template-columns: 1fr;
+  .grid-2col, 
+  .grid-4col, 
+  .grid-equal-2col, 
+  [style*="grid-template-columns"] {
+    grid-template-columns: 1fr !important;
   }
 }
 
@@ -533,6 +538,7 @@ body {
   border: 1px solid var(--color-border);
   border-radius: var(--radius-lg);
   padding: 1.5rem;
+  min-width: 0;
 }
 
 .panel-header {