Theme Configurator (px proportions)

[Tijac]

Hello Prestashoppers   

I have attached a screenshot which points out my issue. 

I would like to know how i can change the proportions of those two images - the slider box on the left has the size i want it to be and theres no problems scaling it up and down as i please. But when it comes the the box(es) on the right, they wont allow me to scale them higher from the "Theme Configurator" Module, than what you see on the attached screenshot. 

Assuming theres a fairly easy way to do this - but how?

- They just needs to "match" the height and width, with the slider...

Regards, Tijac.