Vivaldi only affected?

[n3f]

Not sure if this applies to any other browsers, but I had to make a small change to addTestMarkToTitle() in order to get this working with vivaldi. (It seems like it may be a general solution, but 🤷‍♂️ )

let dataUrl = `<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 100 100'><text y='.9em' font-size='90'>${mark}</text></svg>`;
dataUrl = 'data:image/svg+xml,' + encodeURI(dataUrl);
link.setAttribute(
	'href',
	dataUrl,
);