CSS box-sizing Property
Example
Include padding and border in the element's total width and height:
    #example1 {
    box-sizing: border-box;
}
Try it Yourself »
More "Try it Yourself" examples below.
Definition and Usage
The box-sizing property defines how the width and height of an element are 
calculated: should they include padding and borders, or not.
| Default value: | content-box | 
|---|---|
| Inherited: | no | 
| Animatable: | no. Read about animatable | 
| Version: | CSS3 | 
| JavaScript syntax: | object.style.boxSizing="border-box" Try it | 
Browser Support
The numbers in the table specify the first browser version that fully supports the property.
Numbers followed by -webkit- or -moz- specify the first version that worked with a prefix.
| Property | |||||
|---|---|---|---|---|---|
| box-sizing | 10.0 4.0 -webkit- | 8.0 | 29.0 2.0 -moz- | 5.1 3.2 -webkit- | 9.5 | 
CSS Syntax
box-sizing: content-box|border-box|initial|inherit;
Property Values
| Value | Description | 
|---|---|
| content-box | Default. The width and height properties (and min/max properties) includes only the content. Border and padding are not included | 
| border-box | The width and height properties (and min/max properties) includes content, padding and border | 
| initial | Sets this property to its default value. Read about initial | 
| inherit | Inherits this property from its parent element. Read about inherit | 
More Examples
Example
Specify two bordered boxes side by side:
    div
 {
    
 box-sizing: border-box;
    
 width: 50%;
    border: 5px solid red;
   
 float: left;
 }
Try it Yourself »
Related Pages
CSS tutorial: CSS Box Sizing
HTML DOM reference: boxSizing property

