Calendars appear different on site

I used the calendar widget to install a booking calendar into each page of the website BUT on pages where the widget sidebar doesn't exist, I have included an individual shortcode i.e. [app_worker_monthly_calendar worker_id="5"]

Why do they appear so differently? The widget is the perfect shape, size and configuration - the shortcode is terrible, over-sized, unformatted!

So many inconsistencies with this product!