Step 20 happy flappy penguin

What am i doing wrong please?

.back-mountain{
width: 300px;
height: 300px;
background: linear-gradient(rgb(203, 241, 228) rgb(47, 170, 255));
}

If you have a question about a specific challenge as it relates to your written code for that challenge, just click the Ask for Help button located on the challenge. It will create a new topic with all code you have written and include a link to the challenge also. You will still be able to ask any questions in the post before submitting it to the forum.

Thank you.