Reset view icon is not rendering without custom CSS for background-image path

[paatre]

Environment

$ cat .python-version
3.13

$ uv tree
Resolved 7 packages in 0.55ms
django-leaflet-test v0.1.0
├── django-leaflet v0.31.0
│   └── django v5.1.7
│       ├── asgiref v3.8.1
│       └── sqlparse v0.5.3
└── ruff v0.11.2 (group: dev)

Description

I wanted to test out this package by creating a minimal setup to get a map rendered to a template. And it was really easy to do. No problems with that. But, I do have a problem with a specific thing that is rendered on the map.

The reset view button's icon isn't rendering by default:

It's just a blank white button without any icon.

I managed to render it by adding a custom CSS that adds a background-image directly to the <a> tag: https://github.com/paatre/django-leaflet-test/blob/eb254255de9e2f96d0fa7dea35963ee609445ff2/project/templates/index.html#L18-L20

.leaflet-control-zoom-out.leaflet-bar-part {
    background-image: url("{% static 'leaflet/images/reset-view.png' %}");
}

So I use the reset-view.png from the statics where the image should be rendered from, and it creates a black-bordered square:

I suppose the icon should be rendered by default without any custom CSS but it just isn't. This problem of mine may be a user error on my part but I haven't found a "correct" solution to this problem. What's my issue?