Custom Class Margin on image

Hi,

I’m having some trouble adding a custom class and reducing the margin with a video and picture underneath. I will be using this class in a few locations. I have assigned my class .margin-class and have added this css .margin-class { margin-top: -20px; } but it doens’t seem to work.

I basically want things to look like this Link

I was able to achieve the effect I wanted with this code but was wondering if there was a mote kosher way to achieve. `img.wp-image-743.avia-img-lazy-loading-not-743.avia_image {
padding-top: -px;
border-top-width: -px;
margin-top: -20px;
}`