Cannot override h2 font color

I am trying to add custom CSS to change the h2 font color for my vantage themed site, but it won’t change from the default black. I am able to get the font size to change but not the color. I am using the custom css editor instead of a child theme. Does anyone have any suggestions? I’m using simple code, as shown below.

h2 {
font-size: 20px;
color: #00bcff;
}