the structure is kind of like this
main#editor
div#app-preview
height from flexdiv
address bar thing,height: 48px
div.iframe-wrapper
height: calc(100% - 45px)
i.e. 3px too talliframe
height: 100%
Glitch :・゚✧ test project, top and bottom of ellipse should be round. come to think of it, so should both sides