body {
    /*background-color: #f0f0f0;*/
    /* font-family: Arial; */
    text-align: center;
}

li {
    text-align: center;
    list-style-position: inside;
}

ul {
    color:darkorange
}

h1 {
    color: darkblue;
}

h2 {
    color: darkred;
}

a {
    color: #008000;
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

input:valid {
  background-color: palegreen;
}

input:invalid {
  background-color: lightpink;
}