I agree that there are some (unintended) similarities between Codepen and CodeSandbox, though I never meant to clone Codepen. I also disagree with some similarities you mentioned. I think the logo and the name are similar. The logo was designed by a friend of mine who didn’t even know Codepen. The name was ReactSandbox first, but I didn’t want to lock into React so I renamed to CodeSandbox.
For colors, Codepen and CodeSandbox have a dark theme, but other than that we don’t have the same color scheme at all. The layout is also different since Codepen defaults to editor top, preview bottom instead of horizontal. CodeSandbox does try to mimic a code editor, and I think Codepen aims to do this as well.
I love Codepen and never meant to rip them off, I hope I didn’t leave this impression to others.