body {
    font-family: -apple-system, system-ui, BlinkMacSystemFont, "Segoe UI", Roboto, Ubuntu, sans-serif;
    padding: 0;
    margin: 0;
    line-height: 1.4;
}
.content {
    max-width: 600px;
    margin: 0 auto;
    padding: 12px;
}
h2 {
    margin-top: 2em;
}
h3 {
    margin-top: 1.5em;
}
a {
    color: #03a9f4;
}
.invisible {
    visibility: hidden;
}
.hidden {
    display: none;
}