help targeting color section height

Hi

I’ve been trying to target a color section and to set it to a specific height in pixels. I want to create a colour band.

I gave it an id in the advanced layout builder, but for some reason, i’m not able to target that specific section.

If you can give an idea of how I should structure the css I would be most appreciative.

This is what I tried
#colourband1 .container {height:10px!important;}

also tried

#colourband1 .avia-section { max-height: 10px!important!}

Thank you