What is the glue stuff you use to seal a glass shower panel to the tub?
What you're looking for is clear silicone caulk. you want to peel off the old caulk, scrap the tile with a single edge razor blade to get all the old caulk off, clean with bleach to remove any trace of mildew and let dry. Then apply the caulk and let dry for 24 hours. The caulk can be bought at any home store or hardware. Here's a picture of a popular brand.


It also comes in a tube that doesn't need a caulking gun. Good luck.