body {
      background: linear-gradient(135deg, #232526 0%, #414345 100%);
      /* background-color: #101010; */
      color: #fff;
      font-family: 'Segoe UI', Arial, sans-serif;
      min-height: 100vh;
      margin: 0;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
    }
    h1 {
      margin-bottom: 24px;
      font-size: 2.5rem;
      letter-spacing: 1px;
      text-shadow: 0 2px 8px #0006;
    }
    .form {
      background: rgba(40, 44, 52, 0.95);
      padding: 32px 28px 24px 28px;
      border-radius: 16px;
      box-shadow: 0 4px 24px #0005;
      display: flex;
      flex-direction: column;
      gap: 16px;
      min-width: 320px;
      max-width: 90vw;
    }
    label {
      font-size: 1.1rem;
      margin-bottom: 4px;
    }
    input[type="number"] {
      padding: 10px 12px;
      border-radius: 8px;
      border: 1px solid #555;
      background: #222;
      color: #fff;
      font-size: 1rem;
      margin-bottom: 10px;
      outline: none;
      transition: border 0.2s;
    }
    input[type="number"]:focus {
      border: 1.5px solid #00bcd4;
    }
    button[type="submit"] {
      background: linear-gradient(90deg, #00bcd4 0%, #2196f3 100%);
      color: #fff;
      border: none;
      border-radius: 8px;
      padding: 12px 0;
      font-size: 1.1rem;
      font-weight: 600;
      cursor: pointer;
      margin-top: 10px;
      box-shadow: 0 2px 8px #0003;
      transition: background 0.2s, transform 0.1s;
    }
    button[type="submit"]:hover {
      background: linear-gradient(90deg, #2196f3 0%, #00bcd4 100%);
      transform: translateY(-2px) scale(1.03);
    }
    #result {
      font-size: 1.25rem;
      margin-top: 28px;
      min-height: 32px;
      text-align: center;
      letter-spacing: 0.5px;
    }