*{
    box-sizing:border-box;
}
body{
    font-family:Arial, sans-serif;
    background-color:lightgray;
    color:#1b1b1b;
    margin:0;
}
header{
    background-color:darkblue;
    padding:10px;
}
header h1{
    color:white;
    text-align:center;
    margin:0;
}
main{
    width:85%;
    max-width:1100px;
    margin:40px auto;
    background-color:white;
    border:1px solid lightgray;
    border-radius:10px;
}
main > p{
    text-align:center;
    margin:20px auto;
    background-color:lightgray;
    box-shadow:5px 5px 5px gray;
    width:fit-content;
    padding:15px 30px;
    border-radius:5px;
}
.tarjeta{
    padding:25px;
    list-style-type:decimal;
}