[Markdown Previewer]Last Test can't pass and feedbacks

Tell us what’s happening:
I am working on my Markdown Previewer and the last test can’t pass which is taking account the carriage return. I though the Markdown syntax says: if you want to take carriage return you have to finish your line with two spaces and then press the carriage return.
There is a lot of work to do but can you give me your feedback on this state on the global operation.
Here is the link of the project https://codepen.io/cirediallo/full/GRKZoje

just found for the carriage return. Now some feedback are welcome