body {
  font-family: sans-serif;
  background-color: #1a1a1a;
  color: #f0f0f0;
  margin: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  min-height: 100vh;
}

header {
  width: 100%;
  padding: 1rem;
  background-color: #2c2c2c;
  text-align: center;
  border-bottom: 1px solid #444;
}

.back-link {
  position: absolute;
  top: 1.5rem;
  left: 1.5rem;
  color: #a0a0a0;
  text-decoration: none;
  transition: color 0.3s;
}

.back-link:hover {
  color: #ffffff;
}

h1 {
  margin: 0;
  font-size: 2rem;
}

main {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 1rem;
}

.controls {
  margin-bottom: 1rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  justify-content: center;
}

button {
  background-color: #444;
  color: #f0f0f0;
  border: 1px solid #666;
  padding: 0.5rem 1rem;
  cursor: pointer;
  transition: background-color 0.3s, border-color 0.3s;
  border-radius: 4px;
}

button:hover {
  background-color: #555;
  border-color: #888;
}

button.active {
  background-color: #007bff;
  border-color: #0056b3;
}

#sandbox {
  border: 2px solid #444;
  background-color: #000;
  max-width: 100%;
}

@media (max-width: 600px) {
  h1 {
    font-size: 1.5rem;
  }

  .back-link {
    position: static;
    display: block;
    margin-bottom: 1rem;
    text-align: center;
  }

  .controls {
    flex-direction: column;
  }
}