Camera page layout improvements + More prominent and rewritten disclaimer

[sgwilym]

In an attempt to help address #32:

• This PR simplifies the camera page's layout using flexbox, as there would be problems with the Dynamicland disclaimer text overflowing and being obscured behind the camera view at certain window sizes. This should also make the layout more accommodating for future changes.
• I've taken the liberty of rewriting the Dynamicland disclaimer message -- I felt like the last one didn't do a very good job of clarifying that Paper Programs doesn't have the same depth as Dynamicland, but maybe I've taken something out that others felt was equally important.

Sorry that the diff is a little hard to make sense of -- I've really only wrapped some existing elements in new parents and edited the CSS.

[janpaul123]

Awesome, thank you! 💯 This was easy to review with the ?w=1 URL trick. 😄 And the message you wrote is great!!