Mail that asks for the system's face, as GitHub's does with -apple-system, still read in the app's monospace beside mail in Arial. siv 720e733a lets a document view say what system-ui is; the reader says sans-serif, and so its own sheet names system-ui again. siv 80baffba adds links to the rich text editor: Ctrl+K at a selection, and web addresses typed or pasted. Compose takes them as they are, and they go in the HTML as anchors and in the text after their words.