This is jut a brief introduction into the possibilities to style the JooDB output using CSS. You need basic knowledge "about Cascading Style" Sheets to understand.
In /components/com_joodb/assets/ you will find a css style sheet called joodb.css. This file is included by JooDB and contents basic style information for JooDB.
Normally it is save to change this file directly, because it will not be overwritten by updates. But a good choice can be also to clear the styles in joodb.css and use the frontend-template css to define the output.
JooDB uses container-classes for the different views
.database-list for catalog view
.database-article for single entry view
.database-form for form and edit view
So if you want to change elements in the views take the container classes as selector For example