---
id: 60a3e3396c7b40068ad6998a
title: 步驟 32
challengeType: 0
dashedName: step-32
---
# --description--
通過將 `margin` 設置爲 `auto`，使 `.three` 元素在畫布上居中。
# --hints--
應該將 `margin` 屬性設置爲 `auto`。
```js
const marginFilter = new __helpers.CSSHelp(document).getCSSRules().filter(x => x.style.margin === 'auto');
assert(marginFilter.length === 2);
```
`.three` 元素的 `margin` 值應爲 `auto`。
```js
const threeMargin = new __helpers.CSSHelp(document).getStyle('.three')?.getPropertyValue('margin');
assert(threeMargin === 'auto');
```
# --seed--
## --seed-contents--
```css
.canvas {
width: 500px;
height: 600px;
background-color: #4d0f00;
overflow: hidden;
}
.frame {
border: 50px solid black;
width: 500px;
padding: 50px;
margin: 20px auto;
}
.one {
width: 425px;
height: 150px;
background-color: #efb762;
margin: 20px auto;
}
.two {
width: 475px;
height: 200px;
background-color: #8f0401;
margin: auto;
}
.three {
width: 91%;
height: 28%;
background-color: #b20403;
--fcc-editable-region--
--fcc-editable-region--
}
```
```html
Rothko Painting
```