DatePicker with combined functionality - dropdowns height on mobile?

Hi!

I want to be able to control the height of the dropdown when on a mobile. Currently it takes up the full width and height of the viewport. I have tried to do it using CSS as follows:

[theme.breakpoints.down('md')]: {
      maxHeight: '70vh',
      overflow: 'scroll',
    },

to no avail. How do I reduce the height on scroll when on a mobile? Thanks