I cannot access the explanation, so could someone please tell me why 'lichte' and not 'licht'.
Because "lunch" is a common gender noun, and you need to add an -e to adjectives that premodify common gender nouns.
I echo some thanks, it makes sense! But just to clarify... Do most adjectives before nouns end with -e? Or just the ones before common gender nouns?
Actually, most adjective add the -e, except for those that precede an unspecified het noun (a.k.a. neuter gender noun):
een mooi meisje
het mooie meisje
A noun is specified when it's preceded by:
a definite article (de/het)
a possessive determiner/adjective (mijn, jouw, haar, zijn, etc.)
a demonstrative determiner (deze, dit, etc.)
So if the noun (or adjective+noun) is preceded by one of these words, it's specified, thus you need to add the -e.
At least, that's as far as I can remember! ;)