# Image credits

Both sky photographs are **CC0 / public domain**, so no attribution is legally
required. They are credited here because crediting photographers is the decent
thing to do, and because the next person should know where to get replacements.

| File | Photograph | Author | Source | Licence |
|---|---|---|---|---|
| `sky-day.*`, `sky-day-sm.*` | Bright blue sky with scenic white cloud patterns | Trixia Lao | [Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Bright_blue_sky_with_scenic_white_cloud_patterns.jpg) (originally Pexels) | CC0 |
| `sky-night.*`, `sky-night-sm.*` | Moon in clouds over Kolleröd | W.carter | [Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Moon_in_clouds_over_Koller%C3%B6d.jpg) | CC0 |

## How these files were made

Each original is a very large photograph (the daytime one is 4000x6000). They
were cropped to a wide band and re-encoded to two widths in two formats:

| | width | JPEG | WebP |
|---|---|---|---|
| `sky-day` | 2400 | 228 KB | 90 KB |
| `sky-day-sm` | 1200 | 77 KB | 35 KB |
| `sky-night` | 2400 | 280 KB | 104 KB |
| `sky-night-sm` | 1200 | 41 KB | 11 KB |

`site.css` serves them with `image-set()` (WebP where supported, JPEG
otherwise) and switches to the `-sm` pair below 760px. Day and night are
separate CSS rules scoped by theme, so a visitor only ever downloads the one
they actually see.

## Replacing them

Pick something with **no horizon and no ground** - the hero needs to read as
open sky at any viewport aspect. Keep an area of plain sky near the upper
middle, because that is where the headline sits. Then re-encode at the same
four sizes and keep the filenames.