- [ ] remove dependency: mermaid 
- [ ] use [js-sequence-diagrams](https://github.com/bramp/js-sequence-diagrams)
- [ ] use [flowchart.js](https://github.com/adrai/flowchart.js)
- [ ] use [MathJax](https://github.com/mathjax/MathJax)
- [ ] try to use [LaTeX2HTML5](https://github.com/pyramation/LaTeX2HTML5)