form pops up while loading

Site URL: http://www.gardenclubofoldgreenwich.org

Sometimes when my site is loading a form pops up. I have a button that links to the form, but I don't want it to pop up when it's loading. It happens when my site is taking more time to load (less than 2 seconds when it's bad.) The form box pops up, but it doesn't contain all the text. 

I've tried removing the form and adding it back, but that didn't work. It's very frustrating because it doesn't always pop up so I can't be certain of anything.

Also, I have a markdown box with an embedded google slides presentation in a green box. The problem is that the box has a black border on the left and bottom edge. 

The code creates a square so I can have the square presentation show without the black bars. If I cannot figure out how to get rid of them, I will just put the same border on all the boxes and pretend that it's a design feature!