* {
  font-family: 'Inter', sans-serif;
  box-sizing: border-box;
  color: #333;
  font-size: 100%;
  line-height: 1.5;
}
.lead { font-size: 1.5rem; font-weight: 300; }
.container { margin: 150px auto; max-width: 960px; }
body {
  background: #9fcedf;
  margin: 0;
}
nav {
  --duration: 0.5s;
  --easing: ease-in-out;
  position: absolute;
  top: 0;
  left: 10px;
  width: 220px;
  margin: 20px;
}
nav ol {
  list-style-type: none;
  margin: 0;
  padding: 0;
}
nav li {
  margin: -4px 0 0 0;
}
nav a {
  display: block;
  text-decoration: none;
  background: #fafafa;
  transform-origin: 0 0;
  transition: transform var(--duration) var(--easing), color var(--duration) var(--easing);
  transition-delay: var(--delay-out);
  border-radius: 4px;
  padding: 1em 1.52em;
}
nav a:hover {
  background: #efefef;
}
nav .sub-menu a {
  font-size: 0.9em;
  color: #666666;
  border-left: 2em solid white;
  padding: 0.75em;
  background: linear-gradient(to right, #ddd 2px, #fff 2px);
}
nav .sub-menu a:hover {
  background: linear-gradient(to right, #ddd 2px, #efefef 2px);
}
nav header {
  font-weight: 600;
  display: block;
  background: rgba(255, 255, 255, 0.5);
  transform-origin: 0 0;
  transition: transform var(--duration) var(--easing), color var(--duration) var(--easing);
  transition-delay: var(--delay-out);
  border-radius: 4px;
  padding: 1em 1.52em;
}
nav header span {
  border: none;
  background: transparent;
  font-size: 1.5em;
  padding: 0;
  cursor: pointer;
  line-height: 1;
  float: right;
}
nav footer button {
  position: absolute;
  top: 0;
  left: 0;
  border: none;
  padding: calc(1em - 2px);
  width: 100%;
  transform-origin: 0 0;
  transition: transform var(--duration) var(--easing);
  transition-delay: calc(var(--duration) + (.1s * (var(--count) / 2)));
  cursor: pointer;
  outline: none;
  background: #cdcdcd;
  opacity: 0;
}
nav.closed a,
nav.closed header {
  transform: translateY(calc(var(--top) * -1)) scaleY(0.1) scaleX(0.2);
  transition-delay: var(--delay-in);
  color: transparent;
}
nav.closed footer button {
  transition-delay: 0s;
  transform: scaleY(0.7) scaleX(0.2);
}