Changed item container max-width from 70% to 37% to render attachments at a smaller size

[sabogalc]

Below are screenshot comparisons between SMServer, macOS, the previous attachment loading in MyMessage, and my changed version. This might not be perfect/final so please let me know what you think of it.

[sabogalc]

One unintended/unfortunate side effect of this change is that attachments kind of flash and resize strangely when they load in now. I'm not sure how to go about fixing that.

React.Redux.App.-.Brave.2021-06-29.18-26-19.mp4

Edit - As far as I can see, this pull request fixed the flashing issue in that the flash is now the same color as the background, so it is not visible.

[sabogalc]

I know 37 seems like a super random number, but I tried 35 and it was too small, and I tried 40 and it was too big, so from there I went on to try everything in between, and 37 ended up being the Goldilocks number.

As noted in my original feature request, I initially tested this issue by seeing what percentage of horizontal space a specific vertical image took up on the screen. macOS was 36.18%, and iOS was 36.36%, for an average of 36.27%. Between these three numbers, it would make sense that in my internal testing, 35 was too little, and while the numbers to round down to 36, 37 looked better to my naked eye. Maybe we could also just implement a decimal percentage for max-width, but I had totally forgotten to check for that when I initially made this change. I just kind of eyeballed it, and by chance, my random number selection ended up being fairly close to what I initially measured and observed.

[sabogalc]

Recently, I got a Framework laptop, and it has a 3:2 display rather than the usual 16:9. This is an issue I had with a tapback placement not quite lining up with the URL preview. I don't know if this is due to me running a custom build that has this 37% change, or if it's the 3:2 display, or something else.