The red tinted narrow leaf sword is
Echinodorus tenellus 'Micro'.
You can't go with anything thinner/smaller blades than
Eleocharis parvulus.
Eleocharis acicularis is a bit taller if you want the heigth.
Glossostigma elatinoides will quickly outpace the
E. parvulus/acicularis. If you want something much less aggressive but still retain the scale & appearance, then
Marsilea minuta would be your best bet.
As to what contrasts well with what, I will defer such aquascaping advice to those more fluent in the field.
