Please open the Booking > Settings General page and in "Advanced section" please click on "Show advanced settings of JavaScript loading" link after this please be sure that this checkbox option: "Disable Bootstrap loading on Front-End" is UNCHECKED.
Please open the Booking > Settings General page and in "Advanced section" please click on "Show advanced settings of JavaScript loading" link after this please be sure that this checkbox option: "Disable Bootstrap loading on Front-End" is UNCHECKED.