Is there an alternative to quarter-round or coving at the base of a built-in book case when the new floor butts up to it. I know I'm supposed to leave a gap but I hate to cover it with trim. Clear silicone caulk?

Also... Just wondering...Since we are in the dampest, hottest time of the year, when presumably the wood is at its most swollen, can't I get away with a smaller gap?

thanks for all your great help!

Quarter round or baseshoe is the appropriate trim.