Non so voi, ma quando si tratta di animazioni e grafica io non scomoderei JavaScript…

codice:
<!doctype html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Esempio</title>
<style type="text/css">
    .switchbox {
        position: relative;
        margin: 5px;
        padding: 10px;
        width: 500px;
        height: 200px;
        background: Tan;
    }

    .switchbox .element1,
    .switchbox .element2 {
        position: absolute;
        bottom: 10px;
        left: 10px;
        right: 10px;
        overflow: auto;
    }

    .switchbox .element1,
    .switchbox:hover .element2 {
        height: 180px;
    }

    .switchbox .element1{
        background: Orange;
    }

    .switchbox .element2{
        background: Beige;
        height: 0px;
        overflow: hidden;
        transition: height .5s;
    }
</style>
</head>

<body>

<div class="switchbox"> BOX 1
    <div class="element1">This one is the first element</div>
    <div class="element2">This one is the second element</div>
</div>

<div class="switchbox"> BOX 2
    <div class="element1">This one is the first element</div>
    <div class="element2">This one is the second element</div>
</div>
        
<div class="switchbox"> BOX N
    <div class="element1">This one is the first element</div>
    <div class="element2">This one is the second element</div>
</div>

</body>
</html>