Increase code font size in firefox developer tool

Question

How to increase code fonts in Firefox developer tools? I know that there is a zoom function but I want to set the font size only for the code.

Answer 1

For certain Mozilla versions (I was testing on Mozilla SeaMonkey equivalent to Mozilla Firefox 52 ESR), an explicitly set root element is required.

This will work:

@namespace xul url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
@namespace html url("http://www.w3.org/1999/xhtml");

while this won't:

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
@namespace html url("http://www.w3.org/1999/xhtml");

Once @namespace rules have been set,

you only need to add selectors and styles:

.devtools-monospace,
.CodeMirror,
.CodeMirror pre {
    font-family: "Courier New", monospace !important;
    font-size: 10pt !important;
}