There are already 2 CSS rules to style the <h1>s - one with a pseudo selector, and one without. Add another selector to each of the rules, so that they also style <h2>s

HTML-CSS
1
Challenge: Grouped animals p { font-family: sans-serif; } 
        img {
            max-width: 150px;
        }
        
        h1 {
            font-family: fantasy;
            border-bottom: 1px solid rgb(230, 230, 230);
            padding: 3px;
        }
        
        h1:hover, a:active, a:link {
            background-color: rgb(248, 255, 199);
        }
        h2 {
            font-family:monospace;
            border-bottom: 1px solid rgb(54, 4, 54);
            padding: 3px;
        }
        h2:hover, a:active, a:link {
            background-color: rgb(22, 51, 48);
        }
        
    </style>
</head>
<body>
    
    <h1>Animal group names</h1>
    
    <p>For many species of animals, there are names that we use to refer to a group of them - like a flock of birds. Here are a few you might not know.</p>
    
    <h2>A skulk of foxes</h2>

    <p>Also called a "leash."</p>
    
    <img src="https://www.kasandbox.org/programming-images/animals/fox.png">
    <img src="https://www.kasandbox.org/programming-images/animals/fox.png">
    
    <h2>A clowder of cats</h2>
    
    <p>Also called a "pounce", "glaring", "kindle", or "clutter."</p>
    
    <img src="https://www.kasandbox.org/programming-images/animals/cat.png">
    <img src="https://www.kasandbox.org/programming-images/animals/cat.png">
    
    <p>
    <a href="http://en.wikipedia.org/wiki/List_of_animal_names">Learn more on Wikipedia</a>
    </p>
</body>
2

A link to the problem and a question? Also, the problem provides an “Ask for help” button does some of that for you.