Responsive Web Design: Added hint to Attach a Fallback Value to a CSS…

… Variable (freeCodeCamp#19594)

Added hint to Attach a Fallback Value to a CSS Variable (https://guide.freecodecamp.org/certifications/responsive-web-design/basic-css/attach-a-fallback-value-to-a-css-variable/)

guide/english/certifications/responsive-web-design/basic-css/attach-a-fallback-value-to-a-css-variable/index.md

@@ -3,8 +3,37 @@ title: Attach a Fallback value to a CSS Variable
 ---
 ## Attach a Fallback value to a CSS Variable
 
-This is a stub. <a href='https://github.com/freecodecamp/guides/tree/master/src/pages/certifications/responsive-web-design/basic-css/attach-a-fallback-value-to-a-css-variable/index.md' target='_blank' rel='nofollow'>Help our community expand it</a>.
+<!-- The article goes here, in GitHub-flavored Markdown. Feel free to add YouTube videos, images, and CodePen/JSBin embeds  -->
+We need to add a fallback value of ```black``` to the ```background``` property of the ```.penguin-top``` and ```.penguin-bottom``` classes.
 
-<a href='https://github.com/freecodecamp/guides/blob/master/README.md' target='_blank' rel='nofollow'>This quick style guide will help ensure your pull request gets accepted</a>.
+## Solution
 
-<!-- The article goes here, in GitHub-flavored Markdown. Feel free to add YouTube videos, images, and CodePen/JSBin embeds  -->
+Add a fallback value of ```black``` to the ```background``` property of the ```.penguin-bottom``` class:
+
+```js
+  .penguin-bottom {
+    top: 40%;
+    left: 23.5%;  
+    /* change code below */
+    background: var(--pengiun-skin,black);
+    /* change code above */ 
+    width: 53%;
+    height: 45%;
+    border-radius: 70% 70% 100% 100%;
+  }
+```
+
+Add a fallback value of ```black``` to the ```background``` property of the ```.penguin-top``` class:
+
+```js
+  .penguin-top {
+    top: 10%;
+    left: 25%;
+    /* change code below */
+    background: var(--pengiun-skin,black);
+    /* change code above */  
+    width: 50%;
+    height: 45%;
+    border-radius: 70% 70% 60% 60%;
+  }
+```