I also have a gallery of simple Dash apps for learning here.
If you'd like to learn even more about Plotly Dash, check out my tutorial repo on github!.
If you'd like to tinker with the colors of your app, try using HEX codes from HTML Color Codes.
The assets folder contains a file called favicon.ico -- you can find and download customized favicons here. Just replace the current favicon with a new one.