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

h1, h2, h3 {
  margin: 0;
}

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

main, nav, section, nav a, nav label {
  box-sizing: border-box;
}
header {
  padding: 1em;
}
section {
  padding: 0.5em;
}
main {
  display: flex;
  min-height: 400px;
}
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 {
  text-align: center;
  font-size: 1.3em;
  line-height: 1.3em;
  background-color: #000;
  color: #fff;
  cursor: pointer;
}
nav label > span {
  font-size: 1.4em;
}

nav input, nav label {
  display: none;
}

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

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

input[type=button] {
  background-color: #07a2a0;
  width: 200px;  
  height: 40px;
  display: block;
  border:0;
  color:#fff;
}

input[type=button]:active {
  background-color: #079290;
}

.err {
  color: #fff;
  background-color: #f00;
  position: relative;
  padding: 16px;
  margin-bottom: 10px;
  line-height: 1.3em;
}
.err span {
  font-size: 1.5em;
  font-weight: bold;
}
.err .close {
  font-size: 1.3em;
  position: absolute;
  top:16px;
  right:16px;
  cursor: pointer;
}

#loader {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
  display: grid;
  text-align: center;
  align-content: center;
  background: rgba(0,0,0,0.05);
}
#loader.hidden {
  display: none;
}

@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;
  }
}

.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)
  }
}