To save a note just store it on disk (cmd/ctrl+s). To add images, drag and drop them onto the text area. Remove the contenteditable attribute from <body>, save, and voila, you now have a static lightweight blog post ready to be published! Formatting can be a bit wonky but should work in some browsers (cmd/ctrl+b/i/u). Copy+pasting formatted text can potentially break things a bit.
The two colors are from Solarized. Feel free to download the file and update style/markup to your preference.
Some ideas/variations:
Dark theme: https://jjjjjjjjjjjjjjjjjjjj.github.io/new-note/dark.html
Serif: https://jjjjjjjjjjjjjjjjjjjj.github.io/new-note/serif.html
HN theme: https://jjjjjjjjjjjjjjjjjjjj.github.io/new-note/hn.html
With heading: https://jjjjjjjjjjjjjjjjjjjj.github.io/new-note/with-heading...