freeCodeCamp/curriculum/challenges/english/14-responsive-web-design-22/learn-css-variables-by-building-a-city-skyline/5d822fd413a79914d39e98ce.md

---
id: 5d822fd413a79914d39e98ce
title: Step 6
challengeType: 0
dashedName: step-6
---

# --description--

Also add a `box-sizing` of `border-box` to everything. This will make it so the border you added doesn't add any size to your elements.

# --hints--

You should use the `box-sizing` property.

```js
assert(new __helpers.CSSHelp(document).isPropertyUsed('box-sizing'));
```

You should make use of the existing `*` selector.

```js
// Two selectors create two CSSStyleRule objects
assert.equal(new __helpers.CSSHelp(document).getStyleDeclarations('*').length, 1);
```

All elements should have a `box-sizing` of `border-box`.

```js
const astStyles = new __helpers.CSSHelp(document).getStyle('*');
assert.equal(astStyles.boxSizing, 'border-box');
```

# --seed--

## --seed-contents--

```html
<!DOCTYPE html>
<html>    
  <head>
    <title>City Skyline</title>
    <link href="styles.css" rel="stylesheet" type="text/css" />
  </head>

  <body>
  </body>
</html>
```

```css
--fcc-editable-region--
* {
  border: 1px solid black;
}

--fcc-editable-region--

```