body {
      min-height: 100vh;
      background: linear-gradient(120deg, #e0e7ef 0%, #cfd9df 100%);
      display: flex;
      align-items: center;
      justify-content: center;
      font-family: 'Poppins', Arial, sans-serif;
      margin: 0;
    }
    .calculator {
      background: #f8fafc;
      border-radius: 22px;
      box-shadow: 0 8px 32px rgba(60, 72, 88, 0.10), 0 1.5px 8px rgba(100, 116, 139, 0.08);
      padding: 38px 32px 28px 32px;
      width: 370px;
      max-width: 95vw;
      display: flex;
      flex-direction: column;
      align-items: center;
      transition: box-shadow 0.2s;
      position: relative;
    }
    .toggle-group {
      display: flex;
      gap: 10px;
      margin-bottom: 18px;
    }
    .toggle-btn {
      padding: 8px 24px;
      border: none;
      border-radius: 8px;
      background: #e2e8f0;
      color: #334155;
      font-size: 1rem;
      font-weight: 600;
      cursor: pointer;
      transition: background 0.2s, color 0.2s;
    }
    .toggle-btn.active {
      background: linear-gradient(90deg, #60a5fa 0%, #64748b 100%);
      color: #fff;
    }
    h2 {
      margin: 0 0 8px 0;
      font-weight: 700;
      color: #334155;
      letter-spacing: 1px;
      font-size: 1.7rem;
    }
    .subtitle {
      color: #64748b;
      font-size: 1rem;
      margin-bottom: 18px;
      text-align: center;
    }
    form {
      width: 100%;
      display: flex;
      flex-direction: column;
      gap: 14px;
    }
    label {
      font-size: 1rem;
      color: #475569;
      margin-bottom: 2px;
      font-weight: 500;
    }
    input, select {
      padding: 11px 13px;
      border-radius: 8px;
      border: 1.5px solid #cbd5e1;
      font-size: 1rem;
      background: #f1f5f9;
      transition: border 0.2s, box-shadow 0.2s;
      outline: none;
    }
    input:focus, select:focus {
      border: 1.5px solid #60a5fa;
      background: #fff;
      box-shadow: 0 0 0 2px #60a5fa33;
    }
    button[type="submit"] {
      margin-top: 10px;
      padding: 13px 0;
      border: none;
      border-radius: 8px;
      background: linear-gradient(90deg, #60a5fa 0%, #64748b 100%);
      color: #fff;
      font-size: 1.1rem;
      font-weight: 600;
      letter-spacing: 0.5px;
      cursor: pointer;
      box-shadow: 0 2px 8px rgba(100, 116, 139, 0.10);
      transition: background 0.2s, transform 0.1s;
    }
    button[type="submit"]:hover {
      background: linear-gradient(90deg, #64748b 0%, #60a5fa 100%);
      transform: translateY(-2px) scale(1.03);
    }
    #result {
      margin-top: 24px;
      font-size: 1.08rem;
      color: #334155;
      background: #e2e8f0;
      border-radius: 10px;
      padding: 16px 10px;
      min-height: 32px;
      width: 100%;
      text-align: center;
      box-shadow: 0 1px 4px rgba(100, 116, 139, 0.08);
      font-weight: 500;
      letter-spacing: 0.2px;
    }
    @media (max-width: 500px) {
      .calculator {
        padding: 20px 8px 16px 8px;
        width: 98vw;
      }
    }