Colores de fondo personalizados para cada campo

const response = await fetch(
  'https://api.Firma.dev/functions/v1/signing-request-api/signing-requests',
  {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${process.env.FIRMA_API_KEY}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      workspace_id: workspaceId,
      template_id: templateId,
      recipients: [
        {
          id: 'temp_1',
          first_name: 'Sarah',
          last_name: 'Chen',
          email: 'sarah@example.com',
          designation: 'Firmante',
          order: 1
        },
        {
          id: 'temp_2',
          first_name: 'Mike',
          last_name: 'Torres',
          email: 'mike@example.com',
          designation: 'Firmante',
          order: 2
        }
      ],
      fields: [
        {
          type: 'firma',
          position: { x: 15, y: 80, width: 30, height: 8 },
          page_number: 1,
          required: true,
          recipient_id: 'temp_1',
          background_color: '#E3F2FD'
        },
        {
          type: 'firma',
          position: { x: 55, y: 80, width: 30, height: 8 },
          page_number: 1,
          required: true,
          recipient_id: 'temp_2',
          background_color: '#FFF3E0'
        },
        {
          type: 'date',
          position: { x: 15, y: 90, width: 20, height: 5 },
          page_number: 1,
          required: true,
          recipient_id: 'temp_1',
          background_color: '#E3F2FD'
        },
        {
          type: 'date',
          position: { x: 55, y: 90, width: 20, height: 5 },
          page_number: 1,
          required: true,
          recipient_id: 'temp_2',
          background_color: '#FFF3E0'
        }
      ]
    })
  }
);