Embedded Modal Popup Pages are behind the header

Does anyone know how to make modal poup pages embedded appear in front of the header in wordpress?

Thanks! My last question: where should I input this code?

Yep just target the modal

Hi Jonathan. Its just on modal page.

Should I try this code?

Hi Rodrigo,

Is it just on the modal Page? Otherwise you will need to add

position: relative;

Z-index:2;