The CSS property that defines the number of times an animation should run is animation-iteration-count. By specifying a value, such as an integer or "infinite," you can control how many times the animation repeats. This property is essential for creating looping animations with a specific number of iterations or an indefinite loop.

To ensure that the distance between lines of text is 1.5 times the size of the text, you can use the line-height property in CSS. You can set it to 150%, which is equivalent to 1.5 times the font size. Alternatively, you can use line-height with an em value, like 1.5em, which achieves the same effect.

The backface-visibility property in CSS is particularly useful when creating 3D transformations. When set to hidden, it prevents the back side of an element from being visible, which is essential for 3D transformations where the front and back of an element should not be visible simultaneously.

To emphasize the first line of every paragraph differently from the rest of the content, you should use the ::first-line pseudo-element in CSS. This pseudo-element targets the first line of a block-level element and allows you to apply specific styling to it.

When working on a large-scale project, the BEM (Block Element Modifier) methodology is highly appropriate. BEM encourages the creation of modular and reusable CSS code by structuring classes in a way that makes it easy to understand their purpose. It follows a strict naming convention, which helps maintainability as the project grows.

The primary benefit of using tools like PostCSS in modern web development workflows is that it allows you to write CSS in JavaScript files, which enhances code modularity. PostCSS enables the use of CSS features that might not be available in traditional CSS, making it a powerful tool for optimizing and streamlining your styles.

In the BEM (Block Element Modifier) methodology, elements are represented with a single hyphen - connecting the block and element names. Therefore, the correct way to represent an element named "item" inside a block named "menu" is by using the class .menu-item.

To target devices with retina displays specifically, you can use the @media query and specify the min-device-pixel-ratio property. The value of 2 represents a typical retina display, where each CSS pixel corresponds to 2 physical device pixels. So, the correct option is @media (min-device-pixel-ratio: 2).

To use the attr() function to get the value of a data attribute in CSS, you should specify the attribute's name as an argument within attr(). For example, to retrieve the value of a data attribute named "data-value," you would use attr(data-value). You can then apply this value to a CSS property, such as content or a custom property.

The CSS property used to specify the number of times an animation should run is animation-iteration-count. This property allows you to control how many times an animation sequence repeats. If set to a specific number or "infinite," it determines the animation's iteration count.