#main_container {

width: 450px;

margin: 20px;

margin-left: auto;

margin-right: auto;

padding: 30px;

font-family: sans-serif;

border-radius: 5px;

border: 3px solid #999;

background: #00bfff;

}

#birth_date_input, #age_container {

text-align: center;

margin: 20px;

margin-left: auto;

margin-right: auto;
}

#age_container {

 margin: 40px 5px;

padding: 20px;

border-radius: 5px;

border: 1px solid #999;

font-weight: bolder;

background: #EEE;

font-size: 20px;

line-height: 40px;
}

.hedding {

color: #fff;

text-transform: uppercase;

font-size: 27px;

font-weight: bold;

margin-bottom: 20px;
}

#age span{

color:green;
}

#calculate {

border-radius: 2px;

background-color: #0db9f2;

border: 1px solid #fff;

color: #FFFFFF;

text-align: center;

font-size: 20px;

padding: 8px 27px;

width: 200px;

transition: all 0.5s;

cursor: pointer;

margin: 0 auto;
}

#calculate span {

cursor: pointer;

display: inline-block;

position: relative;

transition: 0.5s;
}

#calculate span:after {

content: ">";

position: absolute;

opacity: 0;

top: 0;

right: -20px;

transition: 0.5s;
}

#calculate:hover span {
padding-right: 25px;
}

#calculate:hover span:after {
    opacity: 1;
    right: 0;
}

#birth_date_input input[type="date" i] {

padding: 5px;

width: 58%;
}