edit

src/Lib/Input.php

@@ -1081,7 +1081,12 @@ class Input
             } else {
                 $xm_on = 'function(){}';
             }
-            $html .= '<div id="' . $param['name'] . '" '.$change.' class="xm-select-demo" style="min-width:150px;width:50%"></div>';
+            $width = '50%';
+
+            if (strstr($param['name'], '_c_')) {
+                $width = '100%';
+            }
+            $html .= '<div id="' . $param['name'] . '" '.$change.' class="xm-select-demo" style="min-width:150px;width:'.$width.'"></div>';
             $html .= '<script>
             $(document).ready(function() {