15. What are pseudo-elements in CSS and what are their uses?

Pseudo-elements allow styling specific parts of elements, such as the first letter, first line, inserting content before or after elements without adding additional HTML code. The most commonly used pseudo-elements are ::before, ::after, ::first-letter, and ::first-line.

/* Examples */
p::first-line {
    font-weight: bold; /* Changes the font weight of the first line of text in <p> */
}

p::first-letter {
    font-size: 200%; /* Changes the font size of the first letter in <p> */
}

.element::before {
    content: "Prefix"; /* Adds content before the element */
}

.element::after {
    content: "Suffix"; /* Adds content after the element */
}