body {
  margin: 0;
  font-family: system-ui;
}

h1, h2, h3 {
  margin: 0.3em 0 0.3em 0;
}

.container {
  width: 900px;
  margin: 0 auto;
}

main, nav, section, nav a, nav label {
  box-sizing: border-box;
}

header {
  padding: 1em;
}
section {
  padding: 0 0.5em 0 0.5em ;
}

main {
  display: flex;
}
section {
  flex: 1;
}
section > div {
  height: 100%;
}

nav {
  display: inline-block;
  background-color: #f1f1f1;
  width: 250px;
}

nav a, nav label {
  width: 100%;  
  display: block;
  color: #000;
  padding: 16px;
  text-decoration: none;
  user-select: none;
}

nav label {
  font-size: 1.2em;
  background-color: #000;
  color: #fff;
  cursor: pointer;
}

nav input, nav label {
  display: none;
}

nav a.active {
  background-color: #07a2a0;
  color: #fff;
}

nav a:hover:not(.active) {
  background-color: #555;
  color: white;
}

@media (max-width: 900px) {
  .container, nav {
    width: 100%;
  }
  main {
    flex-direction: column;
  }
  nav label {
    display: block;
  }
  nav, nav a, nav label {
    width:100%;
  }
  nav > input:not(:checked) ~ a:not(.active) {
    display: none;
  }
}

.grid {
  display: grid;
}
.center {
  text-align: center;
}
.middle {
  align-content: center;
}

.loadspin {
  display: inline-block;
  pointer-events: none;
  width: 2.5em;
  height: 2.5em;
  border: 0.4em solid transparent;
  border-color: #eee;
  border-top-color: #07a2a0;
  border-radius: 50%;
  animation: loadingspin 1s linear infinite;
}

@keyframes loadingspin {
  100% {
    transform: rotate(360deg)
  }
}