html {
  font-size: min(4vmin, 30px);
  padding: 0;
  margin: 0;
  height: 100vh;
  width: 100vw;
}
body {
  padding: 0;
  margin: 0;
  height: 100vh;
  width: 100vw;
  text-align: left;
  background: #cecece;
}

body section {
  width: 600px;
  margin: 5vmin auto;
  border-radius: 5px;
  background: #fff;
  padding: 2vmin;
  font-size: 1.2rem;
  line-height: 1.3rem;
  font-family: Tahoma, Arial;
}

h1, h2, h3 {
  font-size: 1.2rem;
  font-weight: 700;
}
small {
  font-size: 1.1rem;
}
ul {
  padding-left: 0;
  list-style-position: inside;
  list-style-type: circle;
}

#plan iframe {
  width:100%;
  height:30vh;
}

@media screen and (max-width: 660px) {
  body section {
    width: 92vmin;
    margin: 1vmin 2vmin;
  }
}

@media screen and (prefers-color-scheme: dark) {
  body {
    background-color: #333;
  }
  body section {
    background-color: #555;
    color: #cececd;
  }

  a {
    color: #aabbff;
  }
}