This is awesome, I love to see innovation in this space. Just signed up for $5. Coming from an Anki background, I could really use keyboard shortcuts to speed

This is awesome, I love to see innovation in this space. Just signed up for $5. Coming from an Anki background, I could really use keyboard shortcuts to speed review. If this site works well, I would forsee scaling out my usage (I usually review Anki for 30-45 minutes per day). One other thing, there seems to be a large amount of extra vertical space on the review page. It looks like this may be because the rest of the text is using `visibility: hidden`, causing the elements to continue taking up space. Not sure if this is intentional but I think I'd prefer for this to be using something like `display: none` so that it doesn't take up any space at all.