前端面试题及答案：CSS盒子模型与选择器详解

The CSS box model is a fundamental concept in web design that defines the structure of an HTML element. The standard CSS box model consists of content, padding, border, and margin. The width of an element in the standard box model is calculated as the sum of the content width, padding, border, and margin. In contrast, the box model used in older versions of Internet Explorer is different. In this model, the width of an element is calculated as the sum of the content width, border, and padding, but not the margin. This can sometimes lead to layout inconsistencies when designing websites for older IE browsers. The box-sizing property in CSS is used to control how the browser interprets the sizing of an element's box model. By default, the box-sizing property is set to content-box, which follows the W3C standard box model. In this mode, when specifying the height and width of an element, it refers to the content area only. Alternatively, the box-sizing property can be set to border-box, which follows the traditional IE box model. In this mode, the height and width properties of an element refer to the total size of the element, including content, padding, and border. There are various CSS selectors that can be used to target specific elements in a document, such as class selectors, ID selectors, element selectors, and attribute selectors. Some CSS properties, such as font-family, color, and text-align, can be inherited by child elements from their parent elements. This allows for consistent styling throughout a website and reduces the amount of code needed to style each individual element.