Plugin toolbar icon is blurry when used in CKEditor

[AnnaTomanek]

The icon was designed for 16x16px due to GitHub UI: https://github.com/ckeditor/ckeditor5-mermaid/blob/master/theme/icons/insert.svg?short_path=b87e06b#L1

But since CKEditor 5 uses 20px icons, it looks blurry in our own Mermaid integration example in the docs on non-Retina screens:

Looks OK for Retina:

As per @oleq's comment:

If you use 1px strokes in 16px, you get 1.25px in 20px. If you use 2px strokes in 16px you get 2.5px in 20px. There’s no way to get sharp integers in both sizes. So there will always be blur in some case unless we provide two dedicated icon sets.