How would you change the list marker to use a marker image from an external URL?
ul { list-style-image: url('https://example.com/bullet.png'); }
ul { marker-image: url('https://example.com/bullet.png'); }
ul { bullet-image: url('https://example.com/bullet.png'); }
ul { list-marker: url('https://example.com/bullet.png'); }