Tell us what’s happening:
Your code so far
background: var(--red-box, red);
Your browser information:
User Agent is:
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0.
Link to the challenge:
It is fairly common for campers to not understand this challenge at first. Bottom line is that not all browsers will understand css variables so be prepared for that