How to place Dropdown item to be fixed with input element(v-select) on veutify popup modal?

Started with Vuejs before a week, Iam using vuetify(requirement).

Here is the example provided by vuetifyjs for popup modal https://vuetifyjs.com/en/components/dialogs#form

https://codepen.io/pen/?editors=1010 use codepen in above link here it just gives empty workspace I am not sure why.

My problem is, after opening pop modal, click(just open) drop-down select without selecting any element or item when I try scrolling. The Drop down Elements too scrolls along with scroll even.

How can we stop this behavior ?