You mention lists and tables...
About lists, it can't be done as stated in AsciiDoctor Documentation:
Unsupported
Complex AsciiDoc markup is not permitted in attribute values, such as:
As you can see, there it mentions multiple paragraphs, so while @EhmKah answer is a correct way to set a custom styling block, it won't be rendered as expected in a table/list as it's multi-paragraph.
The Built-in CSS class syntax is the way to go [small]#any phrases#
But in order to make this work in a table, you must set the cell type with a specifier in this case, the AsciiDoc specifier denoted by a
This means the cell (or column) will render supported AsciiDoc statements, attributes, etc.
Here's a working example:
[frame="none",grid="none"]
|====
a| image::images\logo.png[] a|[.small]#Autor: {author}#
|====
If you have tons of rows/columns, you don't have to manually apply the a to all of them. You can set the columns you need this behavior this way:
[cols="1a,2a",frame="none",grid="none"]
|====
| image::images\logo.png[] |[.small]#Autor: {author}#
|====
You can check its documentation for more about Column Formatting and you can check the Rendered table with variable widths and alignments sub section for more about AsciiDoc (a) and other specifiers.