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."
Several back, the sentence to write was, "This dress is blue." I had had one marked wrong when I wrote "bleue" on another, so I put it without the e on the end. It was marked wrong, showing an 'e' on the end. Now, this one does not want the 'e'. Which is it? (Yes, I understand 'e' usually means feminine but isn't always used but I've done both for the same subject and had it marked wrong and the reverse shown.)