Function mapToCssModules

src/Offcanvas.js:418–422

(
              classNames('offcanvas-backdrop', backdropClassName),
              cssModule,
            )

            innerRef={this._backdrop}
            cssModule={cssModule}
            className={mapToCssModules(
              classNames('offcanvas-backdrop', backdropClassName),
              cssModule,
            )}
            onClick={this.handleBackdropClick}
            onMouseDown={this.handleBackdropMouseDown}
          />
        ) : (