Our images at cygwin-htdocs/goldstars/img/ seemed large for small icons:

$ wc -c img/*
  3473 img/dungbomb.png
  1074 img/goldstar.png
  1303 img/goldwatch.png
  9382 img/pinkwatch.jpg
   877 img/platinumwatch.jpg
   878 img/plush_hippo.jpg
  1055 img/silverstar.png
 18042 total

so converted them and found they were much smaller in webp format,
and reconverting using the upgraded libwebp package command:

    $ cwebp -blend_alpha 0xffffff img/$i.* -o images/$i.webp

$ wc -c images/*
  220 images/dungbomb.webp
  284 images/goldstar.webp
  286 images/goldwatch.webp
  322 images/pinkwatch.webp
  232 images/platinumwatch.webp
  204 images/plush_hippo.webp
  174 images/silverstar.webp
 1722 total

Updating these would make the site more mobile friendly,
quicker for those on low-bandwidth connections,
and cheaper for those on expensive plans.

---
 goldstars/img/dungbomb.png       | Bin 3473 -> 0 bytes
 goldstars/img/dungbomb.webp      | Bin 0 -> 220 bytes
 goldstars/img/goldstar.png       | Bin 1074 -> 0 bytes
 goldstars/img/goldstar.webp      | Bin 0 -> 284 bytes
 goldstars/img/goldwatch.png      | Bin 1303 -> 0 bytes
 goldstars/img/goldwatch.webp     | Bin 0 -> 286 bytes
 goldstars/img/pinkwatch.jpg      | Bin 9382 -> 0 bytes
 goldstars/img/pinkwatch.webp     | Bin 0 -> 322 bytes
 goldstars/img/platinumwatch.jpg  | Bin 877 -> 0 bytes
 goldstars/img/platinumwatch.webp | Bin 0 -> 232 bytes
 goldstars/img/plush_hippo.jpg    | Bin 878 -> 0 bytes
 goldstars/img/plush_hippo.webp   | Bin 0 -> 204 bytes
 goldstars/img/silverstar.png     | Bin 1055 -> 0 bytes
 goldstars/img/silverstar.webp    | Bin 0 -> 174 bytes
 goldstars/src/award_types.csv    |  14 +++++++-------
 15 files changed, 7 insertions(+), 7 deletions(-)
 delete mode 100644 goldstars/img/dungbomb.png
 create mode 100644 goldstars/img/dungbomb.webp
 delete mode 100644 goldstars/img/goldstar.png
 create mode 100644 goldstars/img/goldstar.webp
 delete mode 100644 goldstars/img/goldwatch.png
 create mode 100644 goldstars/img/goldwatch.webp
 delete mode 100755 goldstars/img/pinkwatch.jpg
 create mode 100644 goldstars/img/pinkwatch.webp
 delete mode 100644 goldstars/img/platinumwatch.jpg
 create mode 100644 goldstars/img/platinumwatch.webp
 delete mode 100644 goldstars/img/plush_hippo.jpg
 create mode 100644 goldstars/img/plush_hippo.webp
 delete mode 100644 goldstars/img/silverstar.png
 create mode 100644 goldstars/img/silverstar.webp