border-box vs content-box
Written byPhuoc Nguyen
Created
03 Sep, 2020
Category
CSS
`border-box` and `content-box` are two values of the `box-sizing` property.
Unlike the `content-box`, the `border-box` value indicates that the dimension of an element will also include the border and padding.Let's assume that we have a div element whose size is
`200px x 100px`, the border and padding are `5px` and `10px` respectively.css
.div {
width: 200px;
border: 5px;
padding: 10px;
}In the content box model, the content inside of element will have the same dimension as the element.
css
.div {
/* ... */
box-sizing: content-box;
}shell
// Content box
◀︎──── 200px ────▶︎
┌───────────────────────────────────────────────────────┐
| |
| ┌───────────────────────────────────────┐ |
| | | |
| | ┌───────────────┐ | |
| Border| Padding | Content | | |
| | | | | |
| 5px | 10px | 200px | 10px | 5px |
|◀︎─────▶︎|◀︎─────────▶︎|◀︎─────────────▶︎|◀︎─────────▶︎|◀︎─────▶︎|
| | | | | |
| | └───────────────┘ | |
| | | |
| └───────────────────────────────────────┘ |
| |
└───────────────────────────────────────────────────────┘In the border box model, the content's dimension has to subtract the border and padding from the element's dimension.
Specifically, the content's width is
`200 - 5 * 2 - 10 * 2 = 170px`.shell
// Border box
◀︎──────────────────────── 200px ────────────────────────▶︎
┌───────────────────────────────────────────────────────┐
| |
| ┌───────────────────────────────────────┐ |
| | | |
| | ┌───────────────┐ | |
| Border| Padding | Content | | |
| | | | | |
| 5px | 10px | 170px | 10px | 5px |
|◀︎─────▶︎|◀︎─────────▶︎|◀︎─────────────▶︎|◀︎─────────▶︎|◀︎─────▶︎|
| | | | | |
| | └───────────────┘ | |
| | | |
| └───────────────────────────────────────┘ |
| |
└───────────────────────────────────────────────────────┘#See also
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Phước Nguyễn