How to show small Modal

I want to show a modal in the small version (not full width and height of the screen) for any size of screen with it’s backdrop, besause it only shows like that for only big screen sizes.

use like this
top: 20% !important;
bottom: 20% !important;
overflow: visible !important;
min-height: 100px !important;
max-height: 260px !important;
width: 100% !important;