CSS box-sizing Property

Posted in CSS Tutorial

Updated on Oct 02, 2024

By Mari Selvan

👁️ 18 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

The box-sizing property in CSS controls how the total width and height of an element are calculated. By default, the width and height of an element are calculated based on its content, padding, and border.

The box-sizing property allows you to change this behavior to simplify layout calculations and avoid issues with elements that have padding and borders.

💡 Syntax

The syntax for the box-sizing property is simple. It can be applied to any block-level or inline-level element.

Syntax

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element {
  box-sizing: value;
}

Here, value specifies how the width and height of the element are calculated.

🎛️ Default Value

The default value of the box-sizing property is content-box.

🏠 Property Values

Value	Description
content-box	The default value. The width and height include only the content of the element. Padding and border are added to the width and height.
border-box	The width and height include the content, padding, and border. This means that any padding and border are included in the element’s total width and height, making it easier to manage layout.

📄 Example

In this example, we'll demonstrate how the box-sizing property affects the width and height of a <div> element with padding and border.

index.html

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<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>CSS box-sizing Example</title>
  <style>
    .box-content {
      box-sizing: content-box;
      width: 200px;
      padding: 20px;
      border: 5px solid black;
    }

    .box-border {
      box-sizing: border-box;
      width: 200px;
      padding: 20px;
      border: 5px solid black;
    }
  </style>
</head>
<body>
  <h1>Box-Sizing Property Example</h1>
  <div class="box-content">
    Content-box: Width is 200px, plus padding and border.
  </div>
  <div class="box-border">
    Border-box: Total width is 200px, including padding and border.
  </div>
</body>
</html>

🖥️ Browser Compatibility

The box-sizing property is widely supported across all modern browsers, including Chrome, Firefox, Safari, Edge, and Opera. This makes it a reliable property to use for controlling element sizing and layout.

🎉 Conclusion

The box-sizing property is a useful tool for controlling how the dimensions of an element are calculated.

By choosing between content-box and border-box, you can simplify your layout calculations and create more predictable and consistent designs. Experiment with both values to see which works best for your specific layout needs and project requirements.