(themes) Add StackOverflow dark and light themes (#2802)

AUTHORS.txt

@@ -294,3 +294,4 @@ Contributors:
 - Michael Newton <miken32@github>
 - Richard Gibson <gibson042@github>
 - Fredrik Ekre <ekrefredrik@gmail.com>
+- Jan Pilzer <Hirse@github>

CHANGES.md

@@ -12,10 +12,16 @@ Dev Improvements:
 
 - chore(dev) add theme picker to the tools/developer tool (#2770) [Josh Goebel][]
 
+New themes:
+
+- *StackOverflow Dark* by [Jan Pilzer][]
+- *StackOverflow Light* by [Jan Pilzer][]
+
 [Fredrik Ekre]: https://github.com/fredrikekre
 [Richard Gibson]: https://github.com/gibson042
 [Josh Goebel]: https://github.com/joshgoebel
 [Taufik Nurrohman]: https://github.com/taufik-nurrohman
+[Jan Pilzer]: https://github.com/Hirse
 
 
 ## Version 10.3.1

src/styles/stackoverflow-dark.css

@@ -0,0 +1,78 @@
+/*!
+ * StackOverflow.com dark style
+ *
+ * @stackoverflow/stacks v0.56.0
+ * https://github.com/StackExchange/Stacks
+ */
+
+.hljs {
+  display: block;
+  overflow-x: auto;
+  padding: 0.5em;
+  color: #ffffff;
+  background: #1c1b1b;
+}
+
+.hljs-comment {
+  color: #999999;
+}
+
+.hljs-keyword,
+.hljs-selector-tag,
+.hljs-meta-keyword,
+.hljs-doctag,
+.hljs-section,
+.hljs-selector-class,
+.hljs-meta,
+.hljs-selector-pseudo,
+.hljs-attr {
+  color: #88aece;
+}
+
+.hljs-attribute {
+  color: v#c59bc1;
+}
+
+.hljs-name,
+.hljs-type,
+.hljs-number,
+.hljs-selector-id,
+.hljs-quote,
+.hljs-template-tag,
+.hljs-built_in,
+.hljs-title,
+.hljs-literal {
+  color: #f08d49;
+}
+
+.hljs-string,
+.hljs-regexp,
+.hljs-symbol,
+.hljs-variable,
+.hljs-template-variable,
+.hljs-link,
+.hljs-selector-attr,
+.hljs-meta-string {
+  color: #b5bd68;
+}
+
+.hljs-bullet,
+.hljs-code {
+  color: #cccccc;
+}
+
+.hljs-deletion {
+  color: #de7176;
+}
+
+.hljs-addition {
+  color: #76c490;
+}
+
+.hljs-emphasis {
+  font-style: italic;
+}
+
+.hljs-strong {
+  font-weight: bold;
+}

src/styles/stackoverflow-light.css

@@ -0,0 +1,78 @@
+/*!
+ * StackOverflow.com light style
+ *
+ * @stackoverflow/stacks v0.56.0
+ * https://github.com/StackExchange/Stacks
+ */
+
+.hljs {
+  display: block;
+  overflow-x: auto;
+  padding: 0.5em;
+  color: #2f3337;
+  background: #f6f6f6;
+}
+
+.hljs-comment {
+  color: #656e77;
+}
+
+.hljs-keyword,
+.hljs-selector-tag,
+.hljs-meta-keyword,
+.hljs-doctag,
+.hljs-section,
+.hljs-selector-class,
+.hljs-meta,
+.hljs-selector-pseudo,
+.hljs-attr {
+  color: #015692;
+}
+
+.hljs-attribute {
+  color: #803378;
+}
+
+.hljs-name,
+.hljs-type,
+.hljs-number,
+.hljs-selector-id,
+.hljs-quote,
+.hljs-template-tag,
+.hljs-built_in,
+.hljs-title,
+.hljs-literal {
+  color: #b75501;
+}
+
+.hljs-string,
+.hljs-regexp,
+.hljs-symbol,
+.hljs-variable,
+.hljs-template-variable,
+.hljs-link,
+.hljs-selector-attr,
+.hljs-meta-string {
+  color: #54790d;
+}
+
+.hljs-bullet,
+.hljs-code {
+  color: #535a60;
+}
+
+.hljs-deletion {
+  color: #c02d2e;
+}
+
+.hljs-addition {
+  color: #2f6f44;
+}
+
+.hljs-emphasis {
+  font-style: italic;
+}
+
+.hljs-strong {
+  font-weight: bold;
+}

tools/developer.html

@@ -148,6 +148,8 @@ <h3>Code</h3>
           <option>solarized-dark.css</option>
           <option>solarized-light.css</option>
           <option>srcery.css</option>
+          <option>stackoverflow-dark.css</option>
+          <option>stackoverflow-light.css</option>
           <option>sunburst.css</option>
           <option>tomorrow-night-blue.css</option>
           <option>tomorrow-night-bright.css</option>