diff --git a/guide/english/certifications/responsive-web-design/basic-css/attach-a-fallback-value-to-a-css-variable/index.md b/guide/english/certifications/responsive-web-design/basic-css/attach-a-fallback-value-to-a-css-variable/index.md
index 0043a1f027..239d9d53cf 100644
--- a/guide/english/certifications/responsive-web-design/basic-css/attach-a-fallback-value-to-a-css-variable/index.md
+++ b/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. Help our community expand it.
-
-This quick style guide will help ensure your pull request gets accepted.
-
+We need to add a fallback value of ```black``` to the ```background``` property of the ```.penguin-top``` and ```.penguin-bottom``` classes.
+
+## Solution
+
+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%;
+ }
+```