Help with format for a logo in Codepen

Hello, I am making a website on Codepen, and I have a logo I would like to use. I have the logo with a transparent background, png format. Whenever I upload it to Codepen (using Dropbox), it still has a white background. What do I need to do? Is it just Codepen, or do I have the wrong format? I will post the link to my pen, although it is changing quite a bit:

The logo link is showing as forbidden. Check the share from dropbox. The coding is good, no problem in there.

Hmmm, ok…how do I fix that? Do I need to use something other than Dropbox?