* {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }

    body {
      font-family: 'Orbitron', sans-serif;
      background: #000; /* pure black */
      color: #00fff7;
      display: flex;
      align-items: center;
      justify-content: center;
      height: 100vh;
      padding: 20px;
    }

    .container {
      background: #0b0b0b; /* very dark black */
      border-radius: 18px;
      padding: 40px 30px;
      box-shadow: 0 0 30px rgba(0, 255, 247, 0.15);
      border: 1px solid rgba(0, 255, 247, 0.2);
      width: 100%;
      max-width: 420px;
      text-align: center;
    }

    h2 {
      font-size: 1.8rem;
      margin-bottom: 25px;
      color: #ffffff;
      text-shadow: 0 0 8px #00fff7;
    }

    input[type="number"], select {
      width: 100%;
      padding: 12px;
      margin: 15px 0;
      border-radius: 10px;
      background: #111;
      color: #00fff7;
      border: 1px solid #00fff740;
      font-size: 1rem;
      box-shadow: inset 0 0 8px #00fff720;
      transition: 0.3s ease;
    }

    input::placeholder {
      color: #00fff770;
    }

    input:focus, select:focus {
      outline: none;
      box-shadow: 0 0 12px #00fff770;
    }

    button {
      margin-top: 20px;
      padding: 12px 28px;
      border: none;
      border-radius: 30px;
      background: #00fff7;
      color: #000;
      font-weight: bold;
      font-size: 1rem;
      cursor: pointer;
      transition: transform 0.2s ease, box-shadow 0.3s ease;
      box-shadow: 0 0 12px #00fff770;
    }

    button:hover {
      transform: scale(1.05);
      box-shadow: 0 0 22px #00fff7;
    }

    #result {
      margin-top: 25px;
      font-size: 1.2rem;
      color: #fff;
      text-shadow: 0 0 5px #00fff7;
    }

    .footer {
  position: fixed;
  bottom: 10px;
  width: 100%;
  text-align: center;
  font-size: 0.9rem;
  color: #00fff7aa;
  text-shadow: 0 0 5px #00fff7;
  font-family: 'Orbitron', sans-serif;
}