html, body {
  height: 100%;
  width: 100%;
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, sans-serif;
  font-size: 1.1em;
}

/*
 * Main content
 */

.container {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  margin-top: 60px;  
}

.info {
  margin-top: 30px;
  margin-bottom: 20px;
  margin-left: 20px;
  margin-right: 20px;
  text-align: center;
  line-height: 1.7em;  
  font-size: 0.8em;
}

h1.title {
  font-size: 2em;
  margin-bottom: 30px;
}

p.requirements {
  opacity: 0.5;
  font-size: 0.8em;
}

.button {
  display: inline-block;
  background-color: rgb(0, 122, 255);  
  color: white;
  border: none;
  border-radius: 12px;
  padding: 20px;
  margin: 4px 2px;
  text-align: center;
  text-decoration: none;  
  font-size: 1em;
  letter-spacing: 1px;  
  margin-bottom: 50px;
}

.button:hover {
  opacity: 0.9;
}

/*
 * Header
 */

.header {
  left: 0;
  top: 0;
  width: 100%;
  text-align: center;  
  background: white;
}

.header ul {
  padding: 0;
  padding-top: 10px;
  padding-bottom: 10px;
  margin: 0;
  list-style-type: none;
}

.header ul li {
  display: inline;
}

.header ul li:not(first-child) {
  margin-left: 20px;
}

.header a {
  text-decoration: none;
  color: black;
}

.header a:hover {
  opacity: 0.8;
}

/**
 * Small screens
 */

@media (min-height: 1200px) {
  .header {
    position: fixed;
  }
  
  .container {
    height: 100%;
    margin-top: 0;
  }
  
  .info {
    margin-left: 0px;
    margin-right: 0px;
    font-size: 1em;
  }
  
  .button {
    margin-bottom: 0;
  }
}

/**
 * Dark mode
 */

@media (prefers-color-scheme: dark) {
  body {
    background: black;
    color: white;
  }
  
  .button {
    background-color: rgb(10, 132, 255);
  }
  
  .header {
    background: black;
  }
  
  .header a {
    color: white;    
  }
}