This form's width is overridden by using the "AJS.params.cf_formWidth" parameter set with JavaScript on the page

Form's height could also be overridden by using "AJS.params.cf_formHeight"

<script>
AJS.params.cf_formWidth = 1300;
AJS.params.cf_formHeight = 400;
</script>

It sets the width of the dialog form to 1300pixels and form height will be 400pixels

On this page we use dynamically calculated form height, but set width to 1300 pixels

<script>
AJS.params.cf_formWidth = 1300;
</script>