Combobox Popup Label Space

On a Combobox with caption label if the popup opens on top of the field, there is a space between the box and the popup.
This is because of the caption label. If you set the label to an empty string, then there is no space between field and popup.
This behavior is also on DatePicker or TimePicker. (See examples on:

Is there any way to change this behavior and to get the Popup to open over the caption label? Some css I can put in the shared-styles.html?

Thanks for your help!

As another example.

If you look at the “Custom DateTime Picker” on the CustomField Examples Page:

The Popup (if opened on top) lays over the Caption of the CustomField.

So to get the same behavior on a combobox with caption (the popup opens on top of the caption) I think it would be possible to wrap the combobox in a CustomField or something else to get it to open the popup without the space of the caption.

But still, maybe there is a solution with some custom style. Anybody?