To determine whether an element should be visible when not facing the screen or not, use the backface-visibility property
Example
<!DOCTYPE html>
<html>
<head>
<style>
.demo1 {
position: relative;
width: 150px;
height: 150px;
background-color: yellow;
perspective: 80px;
margin: 50px;
perspective-origin: left;
transform: rotateY(180deg);
}
.demo2 {
position: absolute;
padding: 20px;
background-color: orange;
transform-style: preserve-3d;
transform: rotateX(45deg);
backface-visibility: visible;
}
</style>
</head>
<body>
<h1>Rotation</h1>
<div class = "demo1">Demo
<div class = "demo2">Demo
</div>
</div>
</body>
</html>