Change background color for Unschedule button in Calendar:

According to UI Guidelines > Components > Buttons > Basic buttons, negative action buttons should have background color class $ez-color-danger or hex color #d92d42 (https://doc.ezplatform.com/en/latest/guidelines/components/buttons/#basic-buttons).

Alternative option would be adding CSS classes btn btn-danger; if applied the other button should have CSS classes btn btn-secondary