Better design

Currently, the design of the badge is not good enough. We need a better design :)

The issue is about improving the badge design in a rating image generator. Look at the existing badge generation code, likely in a file like `generateBadge.js` or similar. Examine the current design logic and output format. Determine what 'better design' means by checking if there are any design specifications or examples in the repository. The work involves graphic design and possibly updating the image generation logic.

索引モデルが issue の本文から書いたものです。