Move Stylesheet definition to Style sheet

Author: TGianella

files/en-us/_redirects.txt

@@ -3605,6 +3605,7 @@
 /en-US/docs/Glossary/Simple_response_header	/en-US/docs/Glossary/CORS-safelisted_response_header
 /en-US/docs/Glossary/Spartan	/en-US/docs/Glossary/Microsoft_Edge
 /en-US/docs/Glossary/Static_property	/en-US/docs/Glossary/Property/JavaScript
+/en-US/docs/Glossary/Stylesheet	/en-US/docs/Glossary/Style_sheet
 /en-US/docs/Glossary/Transferable_objects	/en-US/docs/Web/API/Web_Workers_API/Transferable_objects
 /en-US/docs/Glossary/Transmission_Control_Protocol_(TCP)	/en-US/docs/Glossary/TCP
 /en-US/docs/Glossary/URI/www_vs_non-www_URLs	/en-US/docs/Web/URI/Guides/Choosing_between_www_and_non-www_URLs

files/en-us/_wikihistory.json

@@ -4661,7 +4661,7 @@
     "modified": "2020-03-27T15:58:36.525Z",
     "contributors": ["RafeyIqbalRahman", "Iqbalh11", "Sheppy"]
   },
-  "Glossary/Stylesheet": {
+  "Glossary/Style_sheet": {
     "modified": "2019-12-03T08:33:18.728Z",
     "contributors": ["chrisdavidmills", "nicho110"]
   },

files/en-us/glossary/style_sheet/index.md

@@ -0,0 +1,15 @@
+---
+title: Style sheet
+slug: Glossary/Style_sheet
+page-type: glossary-definition
+sidebar: glossarysidebar
+---
+
+A **Style sheet** (sometimes referred to as a "stylesheet") is a set of CSS rules used to control the layout and design of a webpage or document. _Internal_ stylesheets are placed inside a {{htmlelement("style")}} element inside the {{htmlelement("head")}} of a web document, and _external_ stylesheets are placed inside a separate `.css` file, which is applied to a document by referencing the file inside a {{htmlelement("link")}} element in the document's head.
+
+External stylesheets are generally preferred because they allow you to control the styling of multiple pages from a single place, rather than having to repeat the CSS across each page.
+
+## See also
+
+- [CSS Styling basics](/en-US/docs/Learn_web_development/Core/Styling_basics)
+- Stylesheets on [Wikipedia](<https://en.wikipedia.org/wiki/Style_sheet_(web_development)>)

files/en-us/glossary/stylesheet/index.md

@@ -8,7 +8,7 @@ browser-compat: api.CSSStyleSheet.CSSStyleSheet
 
 {{APIRef("CSSOM")}}
 
-The **`CSSStyleSheet()`** constructor creates a new {{domxref("CSSStyleSheet")}} object which represents a single [Stylesheet](/en-US/docs/Glossary/Stylesheet).
+The **`CSSStyleSheet()`** constructor creates a new {{domxref("CSSStyleSheet")}} object which represents a single [Stylesheet](/en-US/docs/Glossary/Style_sheet).
 
 After constructing a stylesheet the {{domxref("CSSStyleSheet.replace()")}}, {{domxref("CSSStyleSheet.replaceSync()")}}, {{domxref("CSSStyleSheet.insertRule()")}}, and {{domxref("CSSStyleSheet.deleteRule()")}} methods can be used to modify the rules of the new stylesheet.