The width property specifies the content width of an element. However, if you have set a width and include padding or borders, the total width of the element will be affected. Understanding the box model is crucial for accurately controlling the size of elements.

CSS sprites combine multiple images into a single file, reducing the number of HTTP requests made by a browser to fetch individual images. This consolidation significantly improves page load performance, especially for websites with multiple small images. While it doesn't directly impact file size or server-side caching, it plays a crucial role in optimizing web page loading times.

To ensure that each row accommodates the tallest item without stretching the shorter ones, set the grid-auto-rows property on the grid items using minmax with a specified minimum height. This allows the row to adjust based on the content's height while preventing excessive stretching.

CSS-in-JS libraries like Styled Components can use a theme prop to dynamically manage theme-specific styles, providing a convenient way to switch between themes in a large-scale application.

When creating a custom CSS gradient, the first color stop can be defined at the "beginning" position, allowing designers to customize the starting point of the gradient, influencing its overall appearance and visual impact.

Feature detection involves identifying and adapting to the specific capabilities of a browser, ensuring consistent performance across different browsers. It goes beyond identifying versions, focusing on handling capabilities to enhance cross-browser compatibility.

In Styled Components, the extend method is used to create a new styled component based on an existing one, allowing for easy reuse and extension of styles.

The correct option is visibility-print. This CSS property is specifically used in print stylesheets to control the visibility of elements when the document is printed. The visibility-print property helps tailor the content for a better print layout.

The rgba color values include an additional alpha parameter for transparency, allowing you to control the opacity of the color. Hex color values are hexadecimal representations of RGB colors without alpha transparency.

The correct option is 'transition'. The 'transition' property in CSS is used to control the smoothness of changes in properties over a specified duration. By providing a hint to the browser about which property changes will occur, developers can create more fluid and visually appealing transitions on web pages.