how can i change css of owl-date-time calendar control in my angular7 app?

I wanted to change the back ground color of of calendar control content and for buttons. Also i need to change text of cancel and set buttons. Plz let me know any clue to do that.

I was tried to apply css using backdropClass property but don’t see any luck..

<owl-date-time
                        #originDepartureDateTime
                        [hour12Timer]="hour12Timer"
                        [startAt]="DepartureTime || startAt"
                        [backdropClass]="owldtcalendarcontrol"
                    ></owl-date-time>

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Source Url how can i change css of owl-date-time calendar control in my angular7 app?