body {
  background: #121212;
  color: #eee;
  font-family: Arial, sans-serif;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 20px;
}

.container {
  background: #222;
  padding: 30px;
  border-radius: 12px;
  width: 350px;
  text-align: center;
  box-shadow: 0 0 15px #00ffff99;
}

h1 {
  margin-bottom: 20px;
}

.form label {
  display: block;
  margin-bottom: 10px;
  font-weight: bold;
}

fieldset {
  border: none;
  margin: 15px 0;
  text-align: left;
}

fieldset label {
  display: block;
  margin-bottom: 8px;
  font-weight: normal;
}

input[type="number"] {
  width: 60px;
  margin-left: 10px;
  padding: 5px;
  border-radius: 6px;
  border: none;
  font-size: 1rem;
}

button {
  margin-top: 15px;
  padding: 10px 20px;
  background: #00ffff;
  color: #000;
  border: none;
  border-radius: 8px;
  font-weight: bold;
  cursor: pointer;
  transition: background 0.3s ease;
}

button:hover:enabled {
  background: #00cccc;
}

button:disabled {
  background: #444;
  cursor: not-allowed;
}

.result {
  margin-top: 20px;
  font-family: monospace;
  font-size: 1.2rem;
  background: #111;
  padding: 15px;
  border-radius: 8px;
  word-break: break-word;
  min-height: 50px;
}

.copy-btn {
  margin-top: 10px;
}

.copy-msg {
  color: #0f0;
  height: 20px;
  margin-top: 10px;
}