Format and layout

[SmilingWayne]

1. 📚 Formatting: font, font-size, color etc;
2. 📃 Layout: width, height, tabs, insiders etc;
3. 🤔 Other page-prettier stuff

[SmilingWayne]

• New plugin (self-modified via https://github.com/TonyCrane/mkdocs-statistics-plugin/) may look wired if no "h1 header" is presented in .md file. Some have been fixed in update 739d0a0 .