In the Airtech theme, you can edit HTML or add your own CSS to any section.
To do this, you can click the Edit HTML button found on Elementor’s left sidebar when you are in Elementor edit mode.
Note: Please be careful as it’s not recommended to edit HTML if you are not an experienced developer. Please note that it’s not inside support scope to fix issues if they arise from your modification.
You can check the below video on how it works.