How are CSS sprites implemented on a page or website?

CSS sprites are implemented by combining several small images into one large file (sprite), and then displaying the required part of this large image on page elements using CSS.

Main steps:

1. Creating a sprite: All images that need to be combined (icons, small backgrounds, etc.) are placed into a single image. This can be done manually in a graphic editor or with automatic tools/sprite generators.

2. Applying CSS: For each element where you want to "insert" an image from the sprite, the following CSS properties are set:

   • background-image: Specifies the path to the sprite file.
   • background-repeat: no-repeat;: Disables repeating the background image.
   • background-position: Defines the coordinates of the top-left corner of the sprite part to display for this element. These coordinates indicate the offset horizontally and vertically from the top-left corner of the sprite.
   • width and height: Set the dimensions of the area where the sprite part will be displayed. These sizes usually match the size of the original icon or image.

Example of usage for two icons in a sprite:

/* Sprite file: icons.png */

.icon {
  background-image: url('icons.png'); // Path to the sprite file
  background-repeat: no-repeat; // Do not repeat the image
  width: 32px; // Width of the element
  height: 32px; // Height of the element
  display: inline-block; /* Or another way to make the element block/inline-block */
}

/* Icon 1: located in the sprite at 0, 0 */
.icon-home {
  background-position: 0 0;
}

/* Icon 2: located in the sprite at -40px, 0 (for example, if there is an 8px gap between icons) */
.icon-settings {
  background-position: -40px 0;
}

Advantages:

• Reducing HTTP requests: Instead of multiple requests, the browser needs to load only one sprite file, reducing page load time.
• Caching: One large file is cached instead of many small ones.

Disadvantages:

• Support complexity: When adding/changing images, the sprite needs to be recreated, and CSS coordinates updated.
• Not suitable for large or very different images.