#kalender {
 
    width: 1400px;
    margin-left: auto;
    margin-right: auto;
    margin-top: 50px;
    text-align: center;
}
 
body {
 
    padding: 0;
    margin: 0;
}
 
.tuerchen {
 
    float: left;
    margin: 15px;
    width: 200px;
    height: 200px;
    background-color: lightblue;
    cursor: pointer;
 
    /* CSS 3 Animation */
    transition: box-shadow 1s ease;
}
 
.tuerchen:hover {
 
    box-shadow: 10px 10px 5px rgba(0, 0, 0, 0.75);
}
 
.tuerchen img {
 
    width: 200px;
    height: 200px;
    display: none;
}
 
.number {
 
    font-size: 21px;
    font-weight: bold;
    margin-top: 85px;
    font-family: helvetica;
    color: #555;
}