erp5_web_js_style: improve default CSS

Prevent img to increase the page width.

bt5/erp5_web_js_style/SkinTemplateItem/portal_skins/erp5_web_js_style_ui/jsstyle.css.css

@@ -51,6 +51,10 @@ body main fieldset > div > label {
   font-weight: bold;
   min-width: 10%;
 }
+body main img,
+body main video {
+  max-width: 100%;
+}
 body > aside#document_list {
   grid-area: sidebar;
   background-color: #DDD;

bt5/erp5_web_js_style/SkinTemplateItem/portal_skins/erp5_web_js_style_ui/jsstyle.less.bin

@@ -65,6 +65,9 @@ body {
         }
       }
     }
+    img, video {
+      max-width: 100%;
+    }
   }
 
   > aside#document_list {