Quick and dirty dark mode CSS for WordPress Developer Handbook. Use with the Stylus browser extension. Probably full of problems but works on the pages I've tried it on.

developer.wordpress.org DARK MODE CSS

@-moz-document domain("developer.wordpress.org") {

/*Find this on Github Gist: https://gist.github.com/jerclarke/4aad7b92636baec4aae461f2f5820b1a*/

body, 
.single-handbook #primary,
.single-handbook #page {
    background: #fff;
    background: #232323;

}

.single-handbook #secondary {
    background: #212121;
}
body, button, input, select, textarea,
.single-handbook .site-main p, .single-handbook .site-main ol, .single-handbook .site-main ul {
    color: #444;
    color: #ddd;
}

code, pre {
    color: #000;
    color: #fff;
    background-color: #000;
    border: 3px solid #000;
}

div[class*="-table-of-contents-container"] ul li .dashicons {
    background-color: #111;
}
.devhub-wrap .wp-parser-class h1 .arg-default, .devhub-wrap .wp-parser-function h1 .arg-default, .devhub-wrap .wp-parser-hook h1 .arg-default, .devhub-wrap .wp-parser-method h1 .arg-default {
    color: #000000;
    color: #fff;
}
.devhub-wrap .wp-parser-class h1 .arg-name, .devhub-wrap .wp-parser-function h1 .arg-name, .devhub-wrap .wp-parser-hook h1 .arg-name, .devhub-wrap .wp-parser-method h1 .arg-name {
    color: #0f55c8;
    color: #1a71ff;
}

.devhub-wrap .wp-parser-class h1, .devhub-wrap .wp-parser-function h1, .devhub-wrap .wp-parser-hook h1, .devhub-wrap .wp-parser-method h1 {
    color: #24831d;
    color: #30b027;
}

.devhub-wrap .wp-parser-class h1 .arg-type, .devhub-wrap .wp-parser-function h1 .arg-type, .devhub-wrap .wp-parser-hook h1 .arg-type, .devhub-wrap .wp-parser-method h1 .arg-type {
    color: #cd2f23;
    color: #ff3d2f;
}

.devhub-wrap .site-main h2, .devhub-wrap .site-main h3, .devhub-wrap .site-main h4, .devhub-wrap .site-main h5, .devhub-wrap .site-main h6 {
    color: #1e1e1e;
    color: #f7f7f7;
}

.devhub-wrap a {
    color: #21759b;
    color: #2eb7f4;

}

.site-main .table-of-contents {
    border: 1px solid #eee;
    border-color: #1c1c1c;
    
    color: #555d66;
    background-color: #fff;
    background-color: #1c1c1c;
    box-shadow: 0 0 8px rgba(0, 0, 0, 0.1);

}

.devhub-wrap #content table th, .devhub-wrap #content-area table th {
    
    border-bottom: 1px solid #f0f0f0;
    border-color: #111;
    
    background: #f0f0f0;
    background: #1c1c1c;
}

.devhub-wrap #content table, .devhub-wrap #content-area table {
    border: 1px solid #f0f0f0;
    
    border-color: #111;
}

.devhub-wrap #content table td, .devhub-wrap #content-area table td {
    border: 1px solid #f0f0f0;
    border-color: #111;
}
}