creating a stylesheet for a 3rd party site to match my site

Hi
I’ve a client who has a wordpress (enfold) website. She’s recently signed up to use a thirdparty service to manage her bookings (timetap).

The guys at timetap want me to supply them a style sheet so it matches the look of her main site (private link).

Here’s their email request :

We can apply a stylesheet to the header of the embedded scheduler (so the top of this page for Vocal Ovation
Two things to note here. First, the stylesheet has to be hosted on an https link (not http). Second, the stylesheet is injected before the bootstrap stylesheet in the head of the document, so in order to override the bootstrap styles you’ll either need ot use more exact targetting with your style commands or the !important tag.
If you do not have a way to host an https link for the stylesheet, we’d be happy to host it for you. Just send me a copy of the .css file through this thread and I’ll upload it for you and provide you with a link so that you or Julie can add it to her account.
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Is there a quick and easy way to do this?

Thanks again guys