freeCodeCamp/curriculum/challenges/english/01-responsive-web-design/css-flexbox/use-the-flex-basis-property-to-set-the-initial-size-of-an-item.md

---
id: 587d78ae367417b2b2512afd
title: Use the flex-basis Property to Set the Initial Size of an Item
challengeType: 0
videoUrl: 'https://scrimba.com/p/pVaDAv/c3d9nCa'
forumTopicId: 301108
---

# --description--

The `flex-basis` property specifies the initial size of the item before CSS makes adjustments with `flex-shrink` or `flex-grow`.

The units used by the `flex-basis` property are the same as other size properties (`px`, `em`, `%`, etc.). The value `auto` sizes items based on the content.

# --instructions--

Set the initial size of the boxes using `flex-basis`. Add the CSS property `flex-basis` to both `#box-1` and `#box-2`. Give `#box-1` a value of `10em` and `#box-2` a value of `20em`.

# --hints--

The `#box-1` element should have a `flex-basis` property.

```js
assert($('#box-1').css('flex-basis') != 'auto');
```

The `#box-1` element should have a `flex-basis` value of `10em`.

```js
assert(code.match(/#box-1\s*?{\s*?.*?\s*?.*?\s*?flex-basis:\s*?10em;/g));
```

The `#box-2` element should have the `flex-basis` property.

```js
assert($('#box-2').css('flex-basis') != 'auto');
```

The `#box-2` element should have a `flex-basis` value of `20em`.

```js
assert(code.match(/#box-2\s*?{\s*?.*?\s*?.*?\s*?flex-basis:\s*?20em;/g));
```

# --seed--

## --seed-contents--

```html
<style>
  #box-container {
    display: flex;
    height: 500px;
  }

  #box-1 {
    background-color: dodgerblue;
    height: 200px;

  }

  #box-2 {
    background-color: orangered;
    height: 200px;

  }
</style>

<div id="box-container">
  <div id="box-1"></div>
  <div id="box-2"></div>
</div>
```

# --solutions--

```html
<style>
  #box-container {
    display: flex;
    height: 500px;
  }

  #box-1 {
    background-color: dodgerblue;
    height: 200px;
    flex-basis: 10em;
  }

  #box-2 {
    background-color: orangered;
    height: 200px;
    flex-basis: 20em;
  }
</style>

<div id="box-container">
  <div id="box-1"></div>
  <div id="box-2"></div>
</div>
```