body{
    margin: 0;
    font-family: sans-serif;
    display: flex; 
    flex-direction:column;
    align-items: center;
    height: 100vh;
    justify-content: center;
    background: url(https://images.unsplash.com/photo-1511576661531-b34d7da5d0bb?ixlib=rb-1.2.1&ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&auto=format&fit=crop&w=1170&q=80);
    background-size: cover;
    overflow: hidden;

}

h2{
    text-transform: uppercase;
    letter-spacing: 4px;
    font-size: 14px;
    text-align: center;    
}

.clock {
    display: flex;
}

.clock div {
    margin: 5px;
    position: relative;        
}

.clock span{    
    width: 100px;
    height: 80px;
    background-color: slateblue;
    opacity: 80%;
    color: white;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 50px;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
}

.clock .text{
    height: 30px;
    font-size: 10px;
    letter-spacing: 2px;
    background-color: darkblue;
    opacity: 80%;
}

.clock #ampm{
    position: absolute;
    bottom: 0;
    width: 60px;
    height: 30px;
    font-size: 20px;
    background-color: green;
}

/* justify-content center -  horizontolly
    align-items - vertically center
*/

@media only screen and (max-width: 600px) {
    
    .clock span{
        width: 70px;
        height: 70px;
        font-size: 40px;
    }
    .clock #ampm{
        width: 40px;
    }
}