*{
margin: 0;
padding: 0;
box-sizing: border-box;
}
html,body{
height: 100%;
width: 100%;
}

body{
    background-color: #e1e1e1;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;

}

.key{
    border: 1px solid #000;
    background-color: #eee;
    display: inline-flex;
    align-items: center;
    font-size: 20px;
    padding: 20px;
    font-weight: bold;
    flex-direction: column;
    min-width: 150px;
    position: relative;
}

.key small{
    position: absolute;
   top: -26px;
   left: 0;
   text-align: center;
   width: 100%;
   color: #555;
   font-size: 14px;
}