This transcript provides a comprehensive tutorial on how to create CSS variations for Adobe Experience Manager (AEM) custom components and how to enable authors to select these variations within the AEM environment. The presenter begins by recapping the previous tutorial on adding CSS to an AEM custom component and then moves on to explain the creation of CSS variations. The tutorial includes a step-by-step guide on:

1. Understanding CSS Variations: The concept of CSS variations is introduced with examples showing different background colors for a card component to highlight the variations concept.
2. Implementing CSS Variations: Detailed instructions on how to define CSS variations using the BEM (Block Element Modifier) methodology and the Less CSS pre-processor for creating manageable and dynamic stylesheets.
3. Applying Styles to AEM Templates: The process for enabling AEM authors to select these variations through the use of the “style system” is explained. This involves modifying the AEM template’s policy configurations to include the newly created CSS variations, allowing authors to choose a style via a paintbrush icon in the AEM authoring UI.
4. Internal Working of AEM Style System: An in-depth look at how AEM applies the selected styles to components on a page by injecting the corresponding CSS class into the component’s HTML structure, thus altering its appearance according to the selected style variation.

Throughout the tutorial, the presenter emphasizes the practical application of these techniques in AEM development, providing a clear, detailed explanation suitable for beginners. This includes converting CSS files to Less for more sophisticated styling capabilities, modifying component policies to include style options, and the importance of naming conventions for readability and manageabilit