How to link to CSS with htmltools?

Question

I understand htmltools can be used to link to a JavaScript file:

htmltools::tags$script(src = "https://unpkg.com/mapbox-gl-leaflet/leaflet-mapbox-gl.js")

But how would I link to a CSS file, for example:

<link href='https://api.mapbox.com/mapbox-gl-js/v2.11.0/mapbox-gl.css' rel='stylesheet' />