How to make a styled Markdown admonition box in a GitHub Gist?

Use emoji to call the user attention

> :warning: **If you are using mobile browser**: Be very careful here!

Here is list of others emojis (just copy paste):

https://gist.github.com/roachhd/1f029bd4b50b8a524f3c

Or you can also use GitHub markdown:

https://gist.github.com/rxaviers/7360908