*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body{
    margin:0;
    min-height:100vh;
    display:flex;
    flex-direction:column;
    justify-content:center;
    align-items:center;

    text-align:center;
}
h1{
    margin-bottom:100px ;
}
button{
    display:inline-block;
    text-align:center;
    background:#2ab8ed;
    color: #000;
    font-size: 1.5em;
    width:150px;
    height:35px;
    border:none;
    border-radius:20px;
    margin:15px; /* en lugar de auto */
}
h2{
    text-align:center;
    padding:0 15px;
}