style.css

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-1475924156734-496f6cac6ec1?ixlib=rb-1.2.1&ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&auto=format&fit=crop&w=870&q=80");

    background-size: cover;
}

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

}
.clock{
    display:flex;
}

.clock div{

margin: 5px;
position:relative;
}

.clock span{
    width: 100px;
    height:80px;
    background: slateblue;
    opacity: .8;
    color: white;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 50px;
    text-shadow: 2px 2px 4px rgba(0,0,0,.3);
}

.clock .text{
    height: 30px;
    font-size: 10px;
    text-transform: uppercase;
    letter-spacing: 2px;
    background: darkblue;
    opacity: 0.8;
}

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