* {
  box-sizing: border-box;
}

body, html {

  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;

  font-size: 12px;

  height: 100%;
  padding: 0;
  margin: 0;
}

a:link {
  text-decoration: none;
}

.content,
.content > div {
  width: 100%;
  height: 100%;
  overflow: hidden;
}

.content > .message {
  text-align: center;
  display: table;

  font-size: 16px;
  color: #111;
}

.content > .message .note {
  vertical-align: middle;
  text-align: center;
  display: table-cell;
}

.content > .error .details {
  max-width: 500px;
  font-size: 12px;
  margin: 20px auto;
  text-align: left;
}

.content > .error pre {
  border: solid 1px #CCC;
  background: #EEE;
  padding: 10px;
}

.content:not(.with-error) > .error,
.content.with-error > .intro,
.content.with-diagram > .intro {
  display: none;
}


.content .canvas,
.content.with-error .canvas {
  visibility: hidden;
}

.content.with-diagram .canvas {
  visibility: visible;
}

.buttons {
  position: fixed;
  bottom: 20px;
  left: 20px;

  padding: 0;
  margin: 0;
  list-style: none;
}

.buttons > li {
  display: inline-block;
  margin-right: 10px;
}
.buttons > li > a {
  background: #DDD;
  border: solid 1px #666;
  display: inline-block;
  padding: 5px;
}

.buttons a {
  opacity: 0.3;
}

.buttons a.active {
  opacity: 1.0;
}