* {
  box-sizing: border-box;
}

body {
  background-color: #1f1f1f;
  color: white;
  margin-left: auto;
  margin-right: auto;
  max-width: 800px;
  padding-left: 16px;
  padding-right: 16px;
  font-family: monospace;
  font-size: 1rem;
}

form {
  display: inline-block;
}

.main-content {
  text-align: center;
}

.navbar {
  position: sticky;
  top: 0;
}

.navbar ul {
  justify-content: center;
  display: flex;
  list-style: none;
  margin: 0 auto;
  padding: 0;
  background: #1f1f1f;
}

.navbar a {
  display: block;
  padding: 0.75rem 1.25rem;
  color: white;
  text-decoration: none;
  text-align: center;
  font-size: 0.85rem;
}

.navbar a:hover,
.navbar a:focus-visible {
  background: #444444;
  color: white;
}

.navbar a.active {
  background: darkslategrey;
  color: white;
}

.navbar li:not(:first-child) {
  border-left: 1px solid white;
  border-color: darkgray;
}

button {
  padding: 1rem 1rem;
  font-family: monospace;
  font-size: 1rem;
  border-radius: 0.5rem;
  border-color: darkgrey;
  cursor: pointer;
  background: #1f1f1f;
  color: white;
  transition: transform 0.1s, background 0.2s;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
  margin: 0.5rem;
}

button:hover {
  background: darkslategrey;
  transform: translateY(-2px);
}

hr {
  color: darkgray;
}