Custom css to change the divide between 2 blocs of text not working>

Hi I'm trying to change the divide between two different text styles. The coloured headings I entered through coding in order to use a heading style I created, the subtext and grey is just the normal style.So I created my heading styles and then added a code line in order to make the margin underneath this font smaller. It has worked for my three previous headings, but all of a sudden stopped working. You can see in the images it has worked for the yellow title which corresponds to h6, but for this green style (h7) and all the next ones the code doesn't work. I'm including screen captures of the text itself and of the codes used. Please help me I don't understand why it doesn't work.

So are there are better ways of proceeding for what I'm doing, I'm new to all of this and just picked up a couple of tutorials online hence my lack of knowledge on how to do this the best way possible.