Fix horizontal scrollbar issues with images and pre tags

- Force images to 100% width to prevent overflow
- Add overflow-x auto to pre tags while preserving whitespace
- Prevent content elements from causing page-wide horizontal scrollbars

make_post_sell/static/css/common.css

@@ -240,16 +240,23 @@ img {
     height: auto;
 }
 
-/* Prevent content images from causing horizontal scrollbars */
+/* Prevent content from causing horizontal scrollbars */
 .content img,
 .product-content img,
 .well img {
-    max-width: 100%;
-    width: auto;
+    width: 100%;
     height: auto;
     box-sizing: border-box;
 }
 
+.content pre,
+.product-content pre,
+.well pre {
+    max-width: 100%;
+    overflow-x: auto;
+    box-sizing: border-box;
+}
+
 img.logo {
     width: initial;
     max-height: 100px;