Make left-hand navigation into a 1/4 width column
Make left-hand navigation into a 1/4 width column

Since we’ve simplified the left hand nav so much it doesn’t need 1/3 of
the width of the page. By making it smaller we have more space to show
previews of email and letter templates.

alphagov/notifications-admin,alphagov/notifications-admin,gov-cjwaszczuk/notifications-admin,gov-cjwaszczuk/notifications-admin,gov-cjwaszczuk/notifications-admin,alphagov/notifications-admin,gov-cjwaszczuk/notifications-admin,alphagov/notifications-admin