style.css

body{
    background-color: #66CDAA;
}

.container{
    justify-content: center;
    flex-direction: row;
    margin-left: auto;

}

.box{
    width: 490px;
    height: 380px;
    background-color: #FFFFFF;
    margin-left: auto;
    margin-right: auto;
    margin-top: 100px;
    border:solid 3px;
    border-radius:20px;
    border-color: #0000;
}

h1{
    font-family:'Franklin Gothic Medium', 'Arial Narrow', Arial, sans-serif;
    text-align: center;
}

h2{
    font-family:'Franklin Gothic Medium', 'Arial Narrow', Arial, sans-serif;    
    text-align: center;    
}

input{
    width: 105px;
    height: 25px;
    margin-left: 140px;
    text-align: left;
    border: 2px solid #66CDAA;
    border-radius: 6px;
}

label{
    font-size: 18px;
    text-align: left;
    margin-left: 150px;
    font-family:'Franklin Gothic Medium', 'Arial Narrow', Arial, sans-serif; 
}

.btncalcular{
    width: 90px;
    height: 30px;
    margin-left: 280px;
    border: 2px solid #66CDAA;
    border-radius: 6px;
    background-color: #FFFFFF;
    color: #000000;
    font-size: 18px;
    font-family:'Franklin Gothic Medium', 'Arial Narrow', Arial, sans-serif; 

}


.resp{
    font-size: 10x;
    text-align: left;
    margin-left: 290px;
    margin-top: -50px;
    font-family:'Franklin Gothic Medium', 'Arial Narrow', Arial, sans-serif; 
}