Oswald was indeed wearing a light shirt.
He had on a white T-shirt, then the outer shirt (the long-sleeved brown shirt) and then the light-colored jacket. If the jacket is zipped only halfway up and the top half of the brown shirt is unbuttoned, then it seems the white T-shirt would be very noticeable.
First things first, Mr. Brown:
(A) Who told you sir the jacket was only zipped up halfway during the encounter between Tippit and the actual gunman? Source please.
(B) Now, regardless of the light colour of the shirt, which did Not match the dark reddish brown shirt donned by the wrongly accused, How do you account for the difference in the light grey pants worn by the wrongly accused as oppose to the
dark coloured trousers described by Mrs. Markham worn by the actual gunman?
Now, for the record, Mr. Brown, I'm not here to clash with you in spite of our obvious differences in this case as I have come to respect you in spite of those differences. That said, I'm no longer the "rookie" researcher you, Mr. Mack (Gary, RIP), etc encountered in May of 2014 w/the Ben Hur chariot avatar drawn by a team of horses. Mr. Mack flooded my then PM box w/your wrong about
this "kid", you're wrong about
that "kid", etc.
However, upon further reading and immersing myself deeper into this case, suffice it to say the hastily contrived script fed to the general public framing an innocent party does Not pass the test of time. That said, best to you & yours for a safe, healthy & Happy Thanksgiving!
The wrongly accused did Not shoot anybody. Anybody.