Only include Fira CSS on /unsupported/* route

server/server.js

@@ -96,7 +96,8 @@ app.get('/', (req, res) => {
 app.get('/unsupported/:reason', (req, res) => {
   const outdated = req.params.reason === 'outdated';
   res.render('unsupported', {
-    outdated: outdated
+    outdated,
+    fira: true
   });
 });