<link href='https://fonts.googleapis.com/css?family=Playfair Display' rel='stylesheet'><link href='https://fonts.googleapis.com/css?family=Sofia' rel='stylesheet'><link href='https://fonts.googleapis.com/css?family=Alex Brush' rel='stylesheet'><link href='https://fonts.googleapis.com/css?family=Akronim' rel='stylesheet'><link href='https://fonts.googleapis.com/css?family=Annie Use Your Telescope' rel='stylesheet'>
<style>.st2 {font-family: 'Playfair Display';font-size: 42px;}.st3 {font-family: 'Sofia';font-size: 42px;}.st4 {font-family: 'Alex Brush';font-size: 42px;}.st5 {font-family: 'Akronim';font-size: 42px;}.st6 {font-family: 'Annie Use Your Telescope';font-size: 42px;}</style>
<h1 class="st2">'Playfair Display' 1234567890 ABC abc</h1><h1 class="st3">'Sofia' 1234567890 ABC abc</h1><h1 class="st4">'Alex Brush' 1234567890 ABC abc</h1><h1 class="st5">'Akronim' 1234567890 ABC abc</h1><h1 class="st6">'Annie Use Your Telescope'1234567890 ABC abc</h1><link href='https://fonts.googleapis.com/css?family=Playfair Display' rel='stylesheet'><link href='https://fonts.googleapis.com/css?family=Sofia' rel='stylesheet'><link href='https://fonts.googleapis.com/css?family=Alex Brush' rel='stylesheet'><link href='https://fonts.googleapis.com/css?family=Akronim' rel='stylesheet'><link href='https://fonts.googleapis.com/css?family=Annie Use Your Telescope' rel='stylesheet'>
I was going to add for offline support and to avoid what Mario pointed out you can import css files into tiddlywiki and tag them as stylesheets removing the dependance on the internet.
And whilst Mario rightly points out what can be a privacy concern this can be used to your advantage because you could put analytics against your own copy of css to see how far a wiki you distribute propagates.
I would also Imagine Mario would insist if you are going to do this it would be a good ethical practice to inform the users of your wiki of this and allow them to "defeat" it if they wish.