The setLength method is a method of the StringBuffer class in Java. It allows you to alter the length of the character sequence stored in the StringBuffer object. The other options are not related to the setLength method.

The modular CSS methodology that uses the Block, Element, Modifier structure is BEM, which stands for Block, Element, Modifier. BEM is a naming convention that helps create maintainable and predictable CSS code by organizing styles into blocks, elements, and modifiers.

Excessively long and specific selectors in compiled CSS are often caused by overusing nesting in preprocessors like SASS or LESS. While nesting can improve code organization, it can also lead to overly specific selectors that increase file size and reduce maintainability.

The primary purpose of functions in SASS is to calculate mathematical expressions. SASS functions can perform various mathematical operations, making it easy to compute values for CSS properties dynamically. They are valuable for maintaining consistency and making stylesheets more maintainable.

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.

In Flexbox, the justify-content property is used to define how items are aligned along the main axis. It controls the distribution of space between and around items along the main axis and is commonly used to center items horizontally or vertically.

The "+" (Adjacent Sibling) combinator in CSS targets elements that are placed immediately after a specific element. It selects elements that share the same parent and are placed directly after the specified element.

In CSS, the "vertical-align" property is used to control the vertical alignment of inline or inline-block elements within a line box. When set to "baseline," it aligns elements to the baseline of their parent element, which is typically the bottom of the characters within the text.

To create a shadow effect behind an element in CSS, you'd use the drop-shadow filter. This filter adds a shadow to an element, allowing you to control its position, color, and blur.