body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
}
header {
    background-color: #0077cc;
    color: white;
    padding: 1em;
    text-align: center;
}
main {
    padding: 1em;
}
section {
    margin-bottom: 2em;
}
input, button {
    display: block;
    margin: 0.5em 0;
    padding: 0.5em;
    width: 100%;
    max-width: 400px;
}
ul {
    list-style: none;
    padding: 0;
}
li {
    margin: 0.5em 0;
}