Tape both sides of the joint with blue masking tape set about 1/8″
from the joint on either side, then run a bead of clear silicone,
strike it off and really push it in to the joint, smooth the bead with
a finger, then scrape off everything that’s on the tape to clean it
off, pull the tape off at a sharp angle bending back on itself, spritz
a fine mist of water with a couple drops of soap in the water on the
joint, then with a finger dipped in the wet-soapy water press down the
edges of the caulking bead that was lifted up when the tape was
removed. The water keeps the caulk from sticking to whatever is wet.
When you’re done there should be hardly any caulk visible at all.