---
id: 612e89d254fe5d3df7d6693d
title: Step 10
challengeType: 0
dashedName: step-10
---

# --description--

Now that you have reset the `html` box model, you need to pass that on to the elements within as well. To do this, you can set the `box-sizing` property to `inherit`, which will tell the targeted elements to use the same value as the parent element.

You will also need to target the pseudo-elements, which are special keywords that follow a selector. The two pseudo-elements you will be using are the `::before` and `::after` pseudo-elements.

The `::before` selector creates a pseudo-element which is the first child of the selected element, while the `::after` selector creates a pseudo-element which is the last child of the selected element. These pseudo-elements are often used to create cosmetic content, which you will see later in this project.

For now, create a CSS selector to target all elements with `*`, and include the pseudo-elements with `::before` and `::after`. Set the `box-sizing` property to `inherit`.

# --hints--

You should have a `*, ::before, ::after` selector.

```js
assert(new __helpers.CSSHelp(document).getStyle('*, ::before, ::after'));
```

Your `*, ::before, ::after` selector should have the `box-sizing` property set to `inherit`.

```js
assert(new __helpers.CSSHelp(document).getStyle('*, ::before, ::after')?.boxSizing === 'inherit');
```

# --seed--

## --seed-contents--

```html
<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <title>Responsive Web Design Piano</title>
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <link rel="stylesheet" href="./styles.css">
  </head>
  <body>
    <div id="piano">
      <div class="keys">
        <div class="key"></div>
        <div class="key black--key"></div>
        <div class="key black--key"></div>
        <div class="key"></div>
        <div class="key black--key"></div>
        <div class="key black--key"></div>
        <div class="key black--key"></div>

        <div class="key"></div>
        <div class="key black--key"></div>
        <div class="key black--key"></div>
        <div class="key"></div>
        <div class="key black--key"></div>
        <div class="key black--key"></div>
        <div class="key black--key"></div>

        <div class="key"></div>
        <div class="key black--key"></div>
        <div class="key black--key"></div>
        <div class="key"></div>
        <div class="key black--key"></div>
        <div class="key black--key"></div>
        <div class="key black--key"></div>
      </div>
    </div>
  </body>
</html>
```

```css
--fcc-editable-region--
html {
  box-sizing: border-box;
}
--fcc-editable-region--
```
