Pango supports named colors as well as normal RGB colors. See the following reference for named colors: Web colors - Wikipedia
<span color='Beige' background='LightSlateGray'>A text in Beige</span>use pango-view tmp/pango-test.markup --hinting full --markup
dunstify -a "beeper" "Test #$RANDOM" "Here goes Pango Markup:<br><span bgcolor='#00FF007F' foreground='#00FF00'><small>http://www.google.com</small></span>"2018-01-28 12:24:59