misc notes and ramblings
* love too frame-advance 60fps recordings of touhou and count animation frames
* the scrolling background is svg noise :3
* what even are the square things that fly around bosses
* making this responsive is too much effort... you can try zooming i guess
* spellcard tidbits:
* on about 12 seconds left on the timer, cirno shoots lines of 4 bullets instead of 3
* the bullets on the right half are slightly faster than the ones on the left half once they turn: this makes a nice interlacing effect when the bullets meet
* on the normal version, cirno shoots yellow bullets more frequently the closer you are to her
* opacity effects use svg animations
* i had a horrendous hack involving the `feColorMatrix` svg filter, the `filter` css property, and [this trick](https://cohost.org/oatmealine/post/310029-tutorial-cool-custo) to get smooth fading that worked over any background, but [webkit didn't like applying a filter from a data url](https://bugs.webkit.org/show_bug.cgi?id=104169)
* i think uploading the svg and using that url would have worked, but i might as well add the effect directly to the svg to save you the cpu usage - it's morally the same as using an animated image anyways
* also the trick only worked for all dark colors (`alpha = 1-(r+g+b)/3`, overlay with white to fade out) or all light colors (`alpha = (r+g+b)/3`, overlay with black to fade out)
* i tried combining two filters to make it work with all colors (`b,alpha = 1-alpha,b`, overlay with blue to fade out, `b,alpha = alpha,1-b`), but it messed with the colors/alpha a bit