Hi Josef.Lukac,
In situation when the resources for the window will be different size depending on your use case you can set these CSS variables for example like so:

smart-window {
	--smart-window-default-height: auto;
	--smart-window-default-width: 50%;

This way the window will take the half width of the parent container and height will be set depending of the amount of content in it.
Please, do not hesitate to contact us if you have any additional questions.
Best regards,
Yavor Dashev
Smart UI Team