Div height cannot be adjusted

I have a container div with an image inside (actually, two stacked images) that I cannot adjust the height for. Another container div with images follows, and I need to be able to adjust the height. I’ve used various percentages in both the height parameter and maximum height, but it has no effect.

CSS ignores percentage height values in cases where the parent box does not have a fixed (e.g. pixel) height.

Generally, it’s better to let the height of a box be determined by its contents (as is the case when the height is undefined).

I wonder if the stacked images are absolutely positioned? In that case they will not affect the height of the parent box, but you can use a padding trick to create the same effect. This is described (in relation to videos) in the section called Video Aspect Ratio in the Xway User Guide.