How to remove the Description Tab Title

I have been trawling support for some CSS to completely remove the Description Title from a single product page.
I have no need for additional tabs, so these are already removed, but the Description Title is also not required.
See attached screen shot.

The CSS below has already been added to the Theme settings / Custom CSS / Global CSS but with no difference in the page.

}
li#tab-title-description {
display: none;
}

.wd-nav-tabs .description_tab{
display: none;
}