Override server SCSS rules for inputs in guest pages

As the server defines some SCSS rules using "input:not([type='range'])"
the selector is more specific than just "input" used in "guest.css", so
the server SCSS rules took precedence over the guest CSS rules. Now that
selector was added to the guest rules too; as the guest rules are loaded
after the server ones now the guest rules for input elements take
precedence over the server ones.

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>