How do I create customized new admonitions, like for questions and answers?

[furnstahl]

This is addressed in jupyter-book/jupyter-book#1345:

In the Jupyter notebook:

:::{admonition} Extra credit
An "extra credit" exercise is presented here.
:::

Then, in format.css:

.admonition-extra-credit {
    border-left-color: rgba(var(--pst-color-success), 1);
}
.admonition-extra-credit .admonition-title {
    background-color: rgba(var(--pst-color-success), .1)
}
.admonition-extra-credit .admonition-title:before {
    color: rgba(var(--pst-color-success), 1);
    content: '\f19d';
}

[furnstahl]

To find free icons like the graduation-hat used over, see https://fontawesome.com/v6.0/icons?d=gallery&p=1&s=solid&m=free.

[furnstahl]

The local format.css file (or whatever you call it) should be put in _static, which is in (or needs to be created in) the jupyter book root directory.

[furnstahl]

Look here: https://pydata-sphinx-theme.readthedocs.io/en/latest/user_guide/customizing.html for customizing colors.