Hello, 

I'm currently building a course in Canvas that contains HTML/CSS Flip Cards. I learned the code for this from Dr.Nufer's "How to Canvas" website (S/o to the GOAT), which you can find in this link here: https://www.howtocanvas.com/theme-editor/flipcard

The Flip Cards look great, but I'm struggling to make them keyboard accessible. I've tried adding tabindex="0" to the HTML, but every time I save the page, the tabindex disappears. When I use inspect on Google Chrome though and enter it into the HTML, the tabindex feature works. 

I'm wondering if the Canvas LMS doesn't support tabindex? I looked at the Canvas HTML Editor Allowlist page, but I didn't see the tabindex attribute, so I'm assuming this is the case. 

Does anyone have any thoughts or ideas on how to troubleshoot this? 

Any and all feedback is greatly appreciated. 

Thanks!