body {
  margin: 0;
  padding: 0;
  font-family: system-ui, sans-serif;
  background: #000;
  color: #fff;
  display: flex;
  justify-content: center;
  align-items: flex-start;
  min-height: 100vh;
}

.container {
  margin-top: 80px;
  text-align: center;
}

h1 {
  margin-bottom: 20px;
  font-size: 32px;
  color: #ffffff;
}

.card {
  background: #111; /* very dark grey for subtle contrast */
  padding: 24px;
  margin-top: 10px;
  border-radius: 8px;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.6);
  display: inline-block;
  width: 280px;
}

.card h2 {
  margin-top: 0;
  margin-bottom: 16px;
  font-size: 20px;
  color: #dddddd;
}

.btn-primary {
  padding: 10px 18px;
  background: #0078d4;
  border: none;
  border-radius: 6px;
  color: white;
  cursor: pointer;
  font-size: 15px;
  width: 100%;
}

.btn-primary:hover {
  background: #005fa3;
}

.output {
  margin-top: 16px;
  font-weight: bold;
  min-height: 24px;
  color: #ffffff;
}