style.css

*{
    margin: 0;
    padding: 0;
    font-family: 'Montserrat', sans-serif;
}
body{
    background: #000 url(https://images.unsplash.com/photo-1588392382834-a891154bca4d?ixid=MXwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHw%3D&ixlib=rb-1.2.1&auto=format&fit=crop&w=1589&q=80);
    background-attachment: fixed;
    background-blend-mode: hard-light;
}
.container{
    position: absolute;
    top: 80px;
    left: 100px;
    right: 100px;
    bottom: 80px;
    background: url(https://images.unsplash.com/photo-1588392382834-a891154bca4d?ixid=MXwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHw%3D&ixlib=rb-1.2.1&auto=format&fit=crop&w=1589&q=80);
    background-attachment: fixed;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    box-shadow: 0 1px 1px rgba(0,0,0,0.12),
    0 2px 2px rgba(0,0,0,0.12),
     0 4px 4px rgba(0,0,0,0.12),
    0 8px 8px rgba(0,0,0,0.12),
    0 16px 16px rgba(0,0,0,0.12);
}
.time-input{
    position: relative;
    top: 24px;
    padding: 24px;
    z-index: 12;
}
.input-time{
    outline: none;
    border: 1px solid rgb(71, 191, 228);
    height: 100px;
}
.label-time{
    color: #fff;
}

.container h2{
    text-align: center;
    font-size: 10em;
    line-height: 0.7em;
    color: #fff;
    margin-top: -80px;
}
.container h2 span{
    display: block;
    letter-spacing: 6px;
    font-size: 0.2em;
}
.countdown{
    display: flex;
    margin-top: 50px;
}
.countdown div{
    position: relative;
    width: 100px;
    height: 100px;
    line-height: 100px;
    text-align: center;
    background: #333;
    color: #fff;
    margin: 0 15px;
    font-size: 3em;
    box-shadow: 0 1px 1px rgba(0,0,0,0.12),
    0 2px 2px rgba(0,0,0,0.12),
     0 4px 4px rgba(0,0,0,0.12),
     0 8px 8px rgba(0,0,0,0.12),
    0 16px 16px rgba(0,0,0,0.12);
}


.countdown div:before{
    content: "";
    position: absolute;
    bottom: -30px;
    left: 0;
    width: 100%;
    height: 50px;
    background: #1E90FF;
    color: #dddddd;
    font-size: 0.35em;
    line-height: 35px;
}
.countdown #day:before{
    content: 'Ngày';
}
.countdown #hour:before{
    content: 'Giờ';
}
.countdown #minute:before{
    content: 'Phút';
}
.countdown #second:before{
    content: 'Giây';
}

.close{
    display: none;
}