React In-browser markdown editor with file download

I took Bob's Ziroll amazing Learn React Course on scrimba last week and this challenge was perfect for me to practice every notion I learned. I was the first time I build a React app from scratch and I learned a lot about components, props, states, localstorage, effects, dark mode (even if I didn't spend much time on it) etc. I tried to add a few functionalities like the possibility to download your document once saved, or delete a doc by clicking the icon on the sidebar (when the sidebar is open, the button in the header was hidden). I didn't care much about CSS and I feel like my code isn't very great, but it wasn't the purpose of this challenge for me. In the future, when I'll forget about my code, I'd like to rework on this project to improve it and see if it's clear enough for someone else. I use React-mde package and would like to replace it and code my own solution for the editor. Saving with cmd+S would be a nice little feature to add too. Every feedback is welcome! Have a nice day, Rémy