Popover center horizontally, maintain vertical position

I am using a Select with Popover interface. I want to center the popover box horizontally.

I found this css to center it in both directions:

.popover-wrapper .popover-content{
    position: relative !important;
    margin: 0 auto !important;
    left: auto !important;
    top: auto !important;

But I want to maintain the vertical position, and I am unable to figure out how to do that.

Can anyone please help me?

Can anyone please help me with this?