"This dress is light blue."
Translation:Cette robe est bleu clair.
Yes. When you use more than one adjective to designate a single color (like "light blue," "dark green," "pale pink" etc.), neither of the adjectives changes according to the noun it modifies. For example:
Il a les yeux bleu clair et les cheveux brun foncé.
"He has light blue eyes and dark brown hair."
I suspect it'll probably be added.
There are important register distinctions: http://www.french-linguistics.co.uk/grammar/this_that_in_french_ci_la.shtml
And it might be worth nothing that in practice adding the "-ci" constitutes but the slightest glimmer in usage: http://bit.ly/2KL7zXd (with "-là" only a bit more common).
Good point and we need to be patient similarly as our highly sought after DUO MOD contributors have done multiple times. This quote may be of interest to you when encountering future duplicate posts like SyedMuh… in another discussion thread Sitesurf responded this way....."because there are many you can't see full threads from your platform, I would advise you use a PC and reserve your phone or tablet for practice." Syed, who I am certain will not read our comments either, could use this response too if you reply directly. Its hard to imagine that a person can comment but not read all the comments. Not even the original comments. At the very beginning of this discussion thread Ripcurlgirl spelled it out quite clearly and n6zs confirmed it for the doubting.