html,
body {
  margin: 0;
  min-height: 100%;
  font-family: system-ui, sans-serif;
}

header {
  display: flex;
  background: #ddd;
}

header > nav {
  flex: 1;
  display: flex;
}

header > nav a {
  padding: 10px;
  color: #673ab8;
  text-decoration: none;
}

header > nav a:hover {
  background-color: #f1e9ff;
}

header > label {
  display: flex;
  align-items: center;
  padding: 10px;
  color: #555;
  font-size: 80%;
}

header input {
  border: none;
  border-radius: 3px;
  padding: 2px 5px;
  font-size: 100%;
}

.app > section {
  padding: 20px;
}