jsFiddle light theme

Adds a light theme, as well as a theme switcher to the settings

You will need to install an extension such as Tampermonkey, Greasemonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Userscripts to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install a user script manager extension to install this script.

(I already have a user script manager, let me install it!)

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

(I already have a user style manager, let me install it!)

// ==UserScript==
// @name         jsFiddle light theme
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Adds a light theme, as well as a theme switcher to the settings
// @author       Malleys
// @match        https://jsfiddle.net/*
// @grant        none
// ==/UserScript==

const styleSheet = document.createElement("style");
styleSheet.textContent = `
body { background: #f3f5f6; color: #39464E }
header { background: white; border-bottom: 1px solid #cfd6d9; }
header * { color: inherit !important }
.windowLabelCont .panelTidy, .windowLabelCont .windowLabel { color: #7f94a1; }
#editor .gutter { background: #cfd6d9; }
.CodeMirror { color: #39464E; }
.CodeMirror-gutters { background-color: #f3f5f6; }
.CodeMirror-linenumber { color: #c8d2d7; }
.CodeMirror-cursor { border-left: 1px solid black; }
div.CodeMirror span.CodeMirror-matchingbracket,
.CodeMirror-matchingtag { border-color: rgba(36,157,127,.8); }
.cm-searching { background: #ffa; background: rgba(255,255,0,.4) }
.cm-s-default .cm-header { color: #00f }
.cm-s-default .cm-quote { color: #36ac3b }
.cm-negative { color: #FF4D4D }
.cm-positive { color: #36ac3b }
.cm-s-default .cm-keyword { color: #a151d2 }
.cm-s-default .cm-atom { color: #219 }
.cm-s-default .cm-number { color: #ED5C65 }
.cm-s-default .cm-def { color: #f18c16 }
.cm-s-default .cm-variable,
.cm-s-default .cm-variable-2 { color: #2795EE }
.cm-s-default .cm-variable-3 { color: #249D7F }
.cm-s-default .cm-comment { color: #A0A1A7 }
.cm-s-default .cm-string { color: #249D7F }
.cm-s-default .cm-string-2 { color: #ED5C65 }
.cm-s-default .cm-meta { color: #39464E }
.cm-s-default .cm-builtin,
.cm-s-default .cm-qualifier { color: #f18c16 }
.cm-s-default .cm-tag { color: #2795EE }
.cm-s-default .cm-bracket { color: #39464E }
.cm-s-default .cm-attribute { color: #f18c16 }
.cm-s-default .cm-hr { color: #999 }
.cm-s-default .cm-link { color: #2795EE }
.cm-s-default .cm-property,
.cm-s-default .cm-punctuation { color: #a5567f; }
.cm-invalidchar,.cm-s-default .cm-error,
div.CodeMirror span.CodeMirror-nonmatchingbracket { background: #ED5C65; color: #fff; }
.CodeMirror-hints { box-shadow: 0 5px 15px rgba(0,0,0,.1); border: 1px solid #eee;background: #fff; }
.CodeMirror-hint { color: #222; }
.CodeMirror-focused .CodeMirror-selected { background: #d7d4f0; }
.CodeMirror-selected { background: #d9d9d9; }
#sidebar, .twitterCont { background: #fff; border-color: #cfd6d9;; }
#sidebar, #sidebar * { color: inherit !important; }
#sidebar .checkboxCont .checkbox,
.checkboxCont input[type=checkbox]:disabled+.checkbox,
.checkboxCont .checkbox { background: rgba(0,0,0,.1); }
#tabs { border-bottom-color: #cfd6d9; border-top-color: transparent; background: #ffffff; }
#tabs .tabItem.active { box-shadow: 0 1px 0 #f3f5f6, 0 -1px 0 #2e71ff; background: #f3f5f6; }
#tabs a, #tabs a:hover { color: #616367; border-color: #cfd6d9; }
#tabs .tabItem.active a { color: #7f94a1; }
#flash-messages li { box-shadow: 0 10px 10px rgba(0,0,0,.05); color: #1f2227; background: #ffffff }
#flash-messages .flashActions a { background: #EEEEEE; color: #757575; }
#flash-messages .flashActions a:hover { color: #212121 }
#flash-messages .success svg { stroke: #4CAF50 }
#flash-messages .error svg { stroke: #F44336 }
#flash-messages .warning svg { stroke: #FFC107 }
form fieldset { background: #fff; }
#app-updates .badge { color: #fff !important; }
.formHeading h2, form fieldset, form input[type="text"], form input[type="email"],
form input[type="password"], form input[type="url"], .otherLinks a { color: #333 }
#sidebar #profile-segment { border-color: #cfd6d9; }
.commonForm fieldset { background-color: transparent; }
#content { color: #1a1d21; }
.commonForm fieldset input[type="text"], .commonForm fieldset input[type="email"],
.commonForm fieldset input[type="password"], .commonForm fieldset input[type="url"], .commonForm fieldset textarea,
.commonForm fieldset select { background: #fff;color: #1a1d21;box-shadow: 0 0 0 1px #cfd6d9; }
.commonForm fieldset + fieldset { border-color: #cfd6d9; }
#user-top-bar { box-shadow: 0 1px 0 #cfd6d9; background: #f3f5f6; }
#user-top-bar strong, .fiddleList h3 a { color: #1a1d21; }
.sideMenu .newAction { border-color: #cfd6d9; }
.fiddleList h3 .latest { color: #FF9800; }#user-top-bar { box-shadow: 0 1px 0 #cfd6d9; background: #f3f5f6; }
#user-top-bar strong, .fiddleList h3 a { color: #1a1d21; }
.sideMenu .newAction { border-color: #cfd6d9; }
.fiddleList h3 .latest { color: #FF9800; }
form .buttonCont input:disabled, form .buttonCont button:disabled { background: rgba(0, 0, 0, 0.15); }
`;
document.body.append(styleSheet);

const p = document.createElement("p");
p.innerHTML = `
<label class="checkboxCont">
	<input type="checkbox" name="x-darkTheme">
	<span class="checkbox"></span>
	Dark theme
</label>`;
for(const node of $x("//*[@id='editor-options']/h3[contains(text(), 'General')]/following-sibling::div[1]")) {
	node.prepend(p);
}

const checkbox = p.querySelector("input");

checkbox.addEventListener("change", event => {
	forceDarkTheme(checkbox.checked);
});

forceDarkTheme("darkTheme" in localStorage ? localStorage.getItem("darkTheme") == "true" : false);

function forceDarkTheme(force) {
	styleSheet.disabled = force;
	checkbox.checked = force;
	localStorage.setItem("darkTheme", force.toString());
}
function $x(xpath, startNode) {
	var doc = startNode && startNode.ownerDocument || document;
	var result = doc.evaluate(xpath, startNode || doc, null, XPathResult.UNORDERED_NODE_ITERATOR_TYPE);
	var node, nodes = [];
	while(node = result.iterateNext()) nodes.push(node);
	return nodes;
}