Fix checkout page mobile layout and improve word-breaking

- Force single column layout on mobile (768px breakpoint) for checkout page
- Remove aggressive word-break: break-all from general content areas
- Add horizontal scrolling for pre/code tags to preserve technical content
- Clean up redundant word-wrap properties

make_post_sell/static/css/common.css

@@ -282,9 +282,13 @@ section.content {
     max-width: 100%;
     overflow-x: auto;
     box-sizing: border-box;
-    word-wrap: break-word;
     overflow-wrap: break-word;
-    word-break: break-all;
+}
+
+/* Make pre and code tags horizontally scrollable for long content */
+pre, code {
+    overflow-x: auto;
+    white-space: pre;
 }
 
 .mps-button {
@@ -869,13 +873,17 @@ section.checkout-page .well {
     box-sizing: border-box;
 }
 
-@media (max-width: 800px) {
+@media (max-width: 768px) {
     section.checkout-page {
         max-width: 100%;
         margin: 0;
         padding: 0 10px;
         grid-template-columns: 1fr;
     }
+    
+    section.checkout-page:has(.checkout-left) {
+        grid-template-columns: 1fr;
+    }
 }
 
 .coupon {