Removing margin below text

Hello I am trying to remove the margin below the headings at “Treating Acne” etc but my CSS does not seem to work, here is the CSS i used.

h2.ticss-9610cb4f.has-medium-font-size{
margin-bottom: 0px;
}

Can anyone tell me why it did not work and how to fix it?

Thank you!!

The page I need help with: [log in to see the link]