Why Does Styling the Body Element's Background Color Affect the Entire Screen?

Why Styling the Background of the Body Element Affects the Entire Screen

The body element is the root element in HTML documents, and styling its background property has a unique effect that extends beyond the element itself. When you assign a background color to the body, it becomes the backdrop for the entire webpage, covering the entire browser viewport.

According to the CSS specification (http://www.w3.org/TR/CSS21/colors.html), "The background of the root element becomes the background of the canvas and covers the entire canvas." This means that the background color for the body element is applied to the entire page, even though the body element itself may not occupy the entire viewport.

For example, if you set the following CSS rule:

body {
  width: 700px;
  height: 200px;
  border: 5px dotted red;
  background-color: blue;
}

You might expect that the background color would only fill the 700px by 200px area defined by the element's width and height. However, the blue background will instead occupy the entire screen, while the border remains confined to the 700px by 200px dimensions.

This behavior is a fundamental aspect of CSS styling. The body element is the outermost container for all other elements on the page, and its background property sets the backdrop for the entire canvas. While other properties, such as borders, are applied to the element itself, the background property extends to the entire viewport, creating the illusion that the background permeates the entire screen.

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