p5.js-web-editor/styles/components/_editor.scss

.CodeMirror {
	font-family: Inconsolata, monospace;
	height: 100%;
	border: 1px solid $editor-border-color;
}

.CodeMirror-linenumbers {
	padding-right: #{10 / $base-font-size}rem;
}

.CodeMirror-linenumber {
	width: #{35 / $base-font-size}rem;
}

.CodeMirror-lines {
	padding-top: #{25 / $base-font-size}rem;
}

.CodeMirror-line {
	padding-left: #{5 / $base-font-size}rem;
}