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---
id: 5a9d7286424fe3d0e10cad13
title: Attach a Fallback value to a CSS Variable
challengeType: 0
videoUrl: 'https://scrimba.com/c/c6bDNfp'
---
## Description
< section id = 'description' >
When using your variable as a CSS property value, you can attach a fallback value that your browser will revert to if the given variable is invalid.
< strong > Note:< / strong > This fallback is not used to increase browser compatibilty, and it will not work on IE browsers. Rather, it is used so that the browser has a color to display if it cannot find your variable.
Here's how you do it:
< blockquote > background: var(--penguin-skin, black);< / blockquote >
This will set background to black if your variable wasn't set.
Note that this can be useful for debugging.
< / section >
## Instructions
< section id = 'instructions' >
It looks there is a problem with the variables supplied to the < code > .penguin-top< / code > and < code > .penguin-bottom< / code > classes. Rather than fix the typo, add a fallback value of < code > black< / code > to the < code > background< / code > property of the < code > .penguin-top< / code > and < code > .penguin-bottom< / code > classes.
< / section >
## Tests
< section id = 'tests' >
```yml
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tests:
- text: Apply the fallback value of < code > black</ code > to the < code > background</ code > property of the < code > penguin-top</ code > class.
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testString: assert(code.match(/.penguin-top\s*?{[\s\S]*background\s*?:\s*?var\(\s*?--pengiun-skin\s*?,\s*?black\s*?\)\s*?;[\s\S]*}[\s\S]*.penguin-bottom\s{/gi), 'Apply the fallback value of < code > black</ code > to the < code > background</ code > property of the < code > penguin-top</ code > class.');
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- text: Apply the fallback value of < code > black</ code > to the < code > background</ code > property of the < code > penguin-bottom</ code > class.
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testString: assert(code.match(/.penguin-bottom\s*?{[\s\S]*background\s*?:\s*?var\(\s*?--pengiun-skin\s*?,\s*?black\s*?\)\s*?;[\s\S]*}/gi), 'Apply the fallback value of < code > black</ code > to the < code > background</ code > property of the < code > penguin-bottom</ code > class.');
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```
< / section >
## Challenge Seed
< section id = 'challengeSeed' >
< div id = 'html-seed' >
```html
< style >
.penguin {
--penguin-skin: black;
--penguin-belly: gray;
--penguin-beak: yellow;
position: relative;
margin: auto;
display: block;
margin-top: 5%;
width: 300px;
height: 300px;
}
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.penguin-top {
top: 10%;
left: 25%;
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/* change code below */
background: var(--pengiun-skin);
/* change code above */
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width: 50%;
height: 45%;
border-radius: 70% 70% 60% 60%;
}
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.penguin-bottom {
top: 40%;
left: 23.5%;
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/* change code below */
background: var(--pengiun-skin);
/* change code above */
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width: 53%;
height: 45%;
border-radius: 70% 70% 100% 100%;
}
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.right-hand {
top: 0%;
left: -5%;
background: var(--penguin-skin, black);
width: 30%;
height: 60%;
border-radius: 30% 30% 120% 30%;
transform: rotate(45deg);
z-index: -1;
}
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.left-hand {
top: 0%;
left: 75%;
background: var(--penguin-skin, black);
width: 30%;
height: 60%;
border-radius: 30% 30% 30% 120%;
transform: rotate(-45deg);
z-index: -1;
}
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.right-cheek {
top: 15%;
left: 35%;
background: var(--penguin-belly, white);
width: 60%;
height: 70%;
border-radius: 70% 70% 60% 60%;
}
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.left-cheek {
top: 15%;
left: 5%;
background: var(--penguin-belly, white);
width: 60%;
height: 70%;
border-radius: 70% 70% 60% 60%;
}
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.belly {
top: 60%;
left: 2.5%;
background: var(--penguin-belly, white);
width: 95%;
height: 100%;
border-radius: 120% 120% 100% 100%;
}
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.right-feet {
top: 85%;
left: 60%;
background: var(--penguin-beak, orange);
width: 15%;
height: 30%;
border-radius: 50% 50% 50% 50%;
transform: rotate(-80deg);
z-index: -2222;
}
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.left-feet {
top: 85%;
left: 25%;
background: var(--penguin-beak, orange);
width: 15%;
height: 30%;
border-radius: 50% 50% 50% 50%;
transform: rotate(80deg);
z-index: -2222;
}
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.right-eye {
top: 45%;
left: 60%;
background: black;
width: 15%;
height: 17%;
border-radius: 50%;
}
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.left-eye {
top: 45%;
left: 25%;
background: black;
width: 15%;
height: 17%;
border-radius: 50%;
}
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.sparkle {
top: 25%;
left: 15%;
background: white;
width: 35%;
height: 35%;
border-radius: 50%;
}
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.blush-right {
top: 65%;
left: 15%;
background: pink;
width: 15%;
height: 10%;
border-radius: 50%;
}
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.blush-left {
top: 65%;
left: 70%;
background: pink;
width: 15%;
height: 10%;
border-radius: 50%;
}
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.beak-top {
top: 60%;
left: 40%;
background: var(--penguin-beak, orange);
width: 20%;
height: 10%;
border-radius: 50%;
}
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.beak-bottom {
top: 65%;
left: 42%;
background: var(--penguin-beak, orange);
width: 16%;
height: 10%;
border-radius: 50%;
}
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body {
background:#c6faf1;
}
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.penguin * {
position: absolute;
}
< / style >
< div class = "penguin" >
< div class = "penguin-bottom" >
< div class = "right-hand" > < / div >
< div class = "left-hand" > < / div >
< div class = "right-feet" > < / div >
< div class = "left-feet" > < / div >
< / div >
< div class = "penguin-top" >
< div class = "right-cheek" > < / div >
< div class = "left-cheek" > < / div >
< div class = "belly" > < / div >
< div class = "right-eye" >
< div class = "sparkle" > < / div >
< / div >
< div class = "left-eye" >
< div class = "sparkle" > < / div >
< / div >
< div class = "blush-right" > < / div >
< div class = "blush-left" > < / div >
< div class = "beak-top" > < / div >
< div class = "beak-bottom" > < / div >
< / div >
< / div >
```
< / div >
< / section >
## Solution
< section id = 'solution' >
```js
var code = ".penguin-top {background: var(--pengiun-skin, black);} .penguin-bottom {background: var(--pengiun-skin, black);}"
```
< / section >