How to change the font of code block?

Plugins and Custom CSS
#1

I have enabled “rem code blocks” in lab, the custom css of changing code block font then dosen’t work.

.quote {
    font-family: Fira Mono, Cascadia Mono, menlo, monaco;
    font-size:13px
}
.rn-code-node {
	font-family: Fira Mono, monaco, menlo;
}

How to change the custom css?