status-page: Improve title styling

Introduce a .hero-title style class, use it in status page and the demo.

Fixes GNOME/libhandy#388
11 jobs for statuspage in 15 minutes and 15 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Build
passed #1137479
api-visibility

00:00:09

passed #1137481
build-debian-clang

00:03:14

passed #1137480
build-debian-gcc

00:02:26

passed #1137482
build-fedora-gcc

00:04:50

passed #1137483
flatpak
build-flatpak

00:04:30

passed #1137484
flatpak
build-flatpak-glade

00:06:50

 
  Test+Docs
passed #1137485
build-gtkdoc

00:02:42

passed #1137486
unit-test

00:02:33

47.4%
 
  Package
passed #1137487
package-debian-buster

00:02:43

 
  Test Package
passed #1137488
autopkgtest-debian-buster-package

00:02:58

passed #1137489
lintian-debian-buster-package

00:02:37