diff --git a/docs/06.7-Custom-Themes.md b/docs/06.7-Custom-Themes.md
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+# Custom Themes
+CSS in Pepperminty Wiki is managed by 2 principle settings:
+
+Setting			| Meaning
+----------------|--------------------------------------------------------------
+`css`			| The current CSS that should be applied (or the keyword `auto` to signal that the automatic default inbuilt theme should be used instead)
+`css_custom`	| Any additional CSS that should be applied.
+
+Both of these setting also  support a URL instead - in which case a `<link rel="stylesheet" />` will be generated.
+
+Pepperminty Wiki _also_ has a theme gallery system, which can be enabled by including the `feature-theme-gallery` module. This is managed by another handful of settings:
+
+ - `css_theme_autoupdate_url`
+ - `css_theme_autoupdate_interval`
+ - `css_theme_gallery_index_url`
+
+The most important one you'll probably be interested in is `css_theme_gallery_index_url`,  which should be a space-separated list of URLs that each point to a theme index file. Said theme index files can contain any number of theme definitions. Once specified, the theme  gallery can be accessed through a link in the master wiki settings - or directly via the `theme-gallery` action.
+
+Note that the theme gallery obviously needs to make 1 or more external HTTP/S requests in order to function. To this end, a warning message is displayed when you visit the theme gallery to make sure that you're ok with this.
+
+
+## Hosting your own theme gallery
+Although you are welcome to submit your own theme to Pepperminty Wiki's official repository and default theme gallery via a pull request, hosting your own theme gallery is really quite simple. First, you need a theme index JSON file that looks something like this:
+
+```json
+[
+	{
+		"hash": "f2b4c237020e8663f5a4ff6d29a73eaf2bb431d8c82749244a6752467a16f9ce",
+		"id": "none",
+		"name": "No theme",
+		"description": "A special theme with no CSS. Useful if you want to create your own theme from scratch!",
+		"author": "Starbeamrainbowlabs",
+		"author_link": "https://starbeamrainbowlabs.com/",
+		"minversion": "v0.20"
+	},
+	{
+		"hash": "8841461af4c79d365c5792ba3b93e4fae30bed7574d875e1540539f4ec961c8c",
+		"id": "default",
+		"name": "Default",
+		"description": "The default theme.",
+		"author": "Starbeamrainbowlabs",
+		"author_link": "https://starbeamrainbowlabs.com/",
+		"minversion": "v0.20"
+	},
+	{
+		"hash": "071871fdc91cbcb13ca26bb853dbe32ee36e92a7ae69b9fd51f9a93cc37df8c0",
+		"id": "blue",
+		"name": "Blue",
+		"description": "A more blue theme.",
+		"author": "ZestyclosePainting",
+		"author_link": "https://reddit.com/u/ZestyclosePainting",
+		"minversion": "v0.20"
+	}
+]
+```
+
+Each theme present in the gallery should be an object in a top-level array. The 7 keys are as follows:
+
+Key		| Meaning
+--------|--------------------
+`hash`	| The SHA256 hash of the theme file itself.
+`id`	| The id of the theme. No spaces and only lowercase alphanumeric characters + dashes please.
+`name`	| The display name for the theme. Put anything you like here, but it doesn't support HTML.
+`description`	| A sentence or 2 describing the theme.
+`author`		| The name of the author
+`author_link`	| A link to the author's website homepage / social media.
+`minversion`	| The minimum version of Pepperminty Wiki required to run the theme.
+
+Each theme should be in a subfolder alongside the main theme index file with the name corresponding to the theme's id. The theme CSS should be in a file called `theme.css` inside this folder, and the preview images should have the names `preview_small.png` (displayed by default) and `preview_large.png` (displayed when you click on the small preview). Example:
+
+ - themeindex.json
+ - space/
+	 - theme.css
+	 - preview_large.png
+	 - preview_small.png
+ - cheese/
+	 - theme.css
+	 - preview_large.png
+	 - preview_small.png
+ - .....
+
+It is suggested that the theme CSS file have a heading like this:
+
+```css
+/**
+ * @id				default
+ * @name			Default
+ * @description		The default theme.
+ * @author			Starbeamrainbowlabs
+ * @author_link		https://starbeamrainbowlabs.com/
+ * @minversion		v0.20
+ */
+```
diff --git a/docs/README.md b/docs/README.md
index e719691..16b0bac 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -9,6 +9,7 @@
  * **Configuration**
      * [Configuring your instance](06-Configuration.md)
      * [Inter-wiki links](06.5-Interwiki-Links.md)
+     * [Custom Themes](06.7-Custom-Themes.md)
  * [Writing Modules](07-Writing-Modules.md)
  * **References**
 	 * [Configuration Settings](https://starbeamrainbowlabs.com/labs/peppermint/peppermint-config-info.php)
