Today I struggled with a weird behavior of CSS transitions. In some cases they worked and in some not. So I investigated a bit and could find a solution and even kind of an explanation 
My use case was a overlay element whose height should be animated via CSS transitions when opening and closing based on the content it has. The content itself was absolute positioned for several reasons and I had to get the height of all children every time they change. In a previous version the code kind of looked like this:
