.container{
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100%;
}
.card
{
    width: 15rem;
    box-shadow: 0px 10px 30px 0px rgba(0, 0, 0, 0.1);
    transition: opacity 0.2s ease, box-shadow 0.2s ease;
    opacity: 1;
}

.card:hover {
   box-shadow: 0px 0px 10px 0px rgba(0, 0, 0, 0.1);
 }

/* CSS only for examples not required for centering */
.container {
}

.note {
    position: absolute;
    z-index: 10;
    right: 0;
    top: 0;
    padding: 5px;
    background: #eee;
    max-width: 360px;
    border: 1px dotted #bbb;
}

/* show border around full height container */
.h-100 {
    border: 1px dotted #cc2222;
}