diff --git a/docs/source/_static/style.css b/docs/source/_static/style.css
new file mode 100644
index 000000000..726fb5238
--- /dev/null
+++ b/docs/source/_static/style.css
@@ -0,0 +1,3 @@
+.wy-nav-content {
+  max-width: none !important;
+}
\ No newline at end of file
diff --git a/docs/source/_templates/layout.html b/docs/source/_templates/layout.html
new file mode 100644
index 000000000..7488ec4aa
--- /dev/null
+++ b/docs/source/_templates/layout.html
@@ -0,0 +1,4 @@
+{% extends "!layout.html" %}
+{% block extrahead %}
+    <link href="{{ pathto("_static/style.css", True) }}" rel="stylesheet" type="text/css">
+{% endblock %}
\ No newline at end of file
diff --git a/docs/source/conf.py b/docs/source/conf.py
index f16cf5ae6..742444bfc 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -10,7 +10,7 @@ author = 'Martin Rotter'
 # -- General configuration ---------------------------------------------------
 # https://www.sphinx-doc.org/en/master/usage/configuration.html#general-configuration
 
-extensions = ['sphinx.ext.extlinks']
+extensions = ['myst_parser', 'sphinx.ext.extlinks']
 templates_path = ['_templates']
 exclude_patterns = [ 'old_docs' ]
 
@@ -20,4 +20,29 @@ exclude_patterns = [ 'old_docs' ]
 html_theme = 'sphinx_rtd_theme'
 html_static_path = ['_static']
 html_logo = '../../resources/graphics/rssguard.png'
-html_favicon = '../../resources/graphics/rssguard.ico'
\ No newline at end of file
+html_favicon = '../../resources/graphics/rssguard.ico'
+
+html_theme_options = {
+  'collapse_navigation': False,
+  'sticky_navigation': True,
+  'navigation_depth': -1,
+  'includehidden': True,
+  'titles_only': False
+}
+
+myst_enable_extensions = [
+  "amsmath",
+  "attrs_inline",
+  "colon_fence",
+  "deflist",
+  "dollarmath",
+  "fieldlist",
+  "html_admonition",
+  "html_image",
+  "linkify",
+  "replacements",
+  "smartquotes",
+  "strikethrough",
+  "substitution",
+  "tasklist",
+]
\ No newline at end of file
diff --git a/docs/source/donations.md b/docs/source/donations.md
new file mode 100644
index 000000000..8c723736a
--- /dev/null
+++ b/docs/source/donations.md
@@ -0,0 +1,3 @@
+Donations
+=========
+You can support author of RSS Guard via [donations](https://github.com/sponsors/martinrotter).
\ No newline at end of file
diff --git a/docs/source/donations.rst b/docs/source/donations.rst
deleted file mode 100644
index 9debd017b..000000000
--- a/docs/source/donations.rst
+++ /dev/null
@@ -1,6 +0,0 @@
-:tocdepth: 2
-
-Donations
-=========
-
-You can support author of RSS Guard via `donations https://github.com/sponsors/martinrotter`.
\ No newline at end of file
diff --git a/docs/source/downloads.md b/docs/source/downloads.md
new file mode 100644
index 000000000..7c0f847ad
--- /dev/null
+++ b/docs/source/downloads.md
@@ -0,0 +1,11 @@
+Downloads
+=========
+Official place to download RSS Guard is at [Github Releases page](https://github.com/martinrotter/rssguard/releases). You can also download the [development (beta) build](https://github.com/martinrotter/rssguard/releases/tag/devbuild), which is updated automatically every time the source code is updated.
+
+RSS Guard is also available in [repositories of many Linux distributions](https://repology.org/project/rssguard/versions), and via [Flathub](https://flathub.org/about).
+
+The are two different flavors:
+* [Regular](https://flathub.org/apps/details/io.github.martinrotter.rssguard): Includes an (almost) full-blown integrated web browser (built with `-DUSE_WEBENGINE=ON`).
+* [Lite](https://flathub.org/apps/details/io.github.martinrotter.rssguardlite): Includes simpler, safer (and less memory hungry integrated web browser (built with `-DUSE_WEBENGINE=OFF`).
+
+I highly recommend to download RSS Guard only from trusted sources.
\ No newline at end of file
diff --git a/docs/source/downloads.rst b/docs/source/downloads.rst
deleted file mode 100644
index 978253a38..000000000
--- a/docs/source/downloads.rst
+++ /dev/null
@@ -1,12 +0,0 @@
-Downloads
-=========
-
-Official place to download RSS Guard is at `Github Releases page <https://github.com/martinrotter/rssguard/releases>`_. You can also download the `development (beta) build <https://github.com/martinrotter/rssguard/releases/tag/devbuild>`_, which is updated automatically every time the source code is updated.
-
-RSS Guard is also available in `repositories of many Linux distributions <https://repology.org/project/rssguard/versions>`_, and via `Flathub <https://flathub.org/about>`_.
-
-The are two different flavors:
- * `Regular <https://flathub.org/apps/details/io.github.martinrotter.rssguard>`_: Includes an (almost) full-blown integrated web browser (built with ``-DUSE_WEBENGINE=ON``).
- * `Lite <https://flathub.org/apps/details/io.github.martinrotter.rssguardlite>`_: Includes simpler, safer (and less memory hungry integrated web browser (built with ``-DUSE_WEBENGINE=OFF``).
-
-I highly recommend to download RSS Guard only from trusted sources.
\ No newline at end of file
diff --git a/docs/source/features/filters.md b/docs/source/features/filters.md
new file mode 100644
index 000000000..d827e14de
--- /dev/null
+++ b/docs/source/features/filters.md
@@ -0,0 +1,261 @@
+Article Filtering
+=================
+Sometimes you need to automatically tweak the incoming article - mark it starred, remove ads from its contents, or simply ignore it. That's where article filtering feature comes in.
+
+## `Article filters` dialog
+The dialog seen below offers you a way of managing your article filters. You can assign single filter to multiple feeds.
+
+`Test` button tests selected filter against existing messages. `Process checked feeds` runs the filter against messages from checked feeds.
+
+<img alt="alt-img" src="images/filters-dialog.png" width="600px">
+
+## Writing article filter
+Article filters are small scripts which are executed automatically when articles/feeds are downloaded. Article filters are `JavaScript` pieces of code which must provide function with prototype:
+
+```js
+function filterMessage() { }
+```
+
+The function should be fast and must return values which belong to enumeration `FilteringAction`.
+
+Each article is accessible in your script via global variable named `msg` of type `MessageObject`, see [this file](https://github.com/martinrotter/rssguard/blob/master/src/librssguard/core/messageobject.h) for the declaration. Some properties are writeable, allowing you to change contents of the article before it is written to RSS Guard DB. You can mark article important, change its description, perhaps change author name or even assign some label to it!!!
+
+Some attributes (`read/unread/starred` states) are synchronized back to your account's server - so you can for example mark some articles as starred and the change will be propagated back to TT-RSS server if you use TT-RSS.
+
+A special placeholders can be used in article filters.
+
+There is also a special variable named `utils`. This variable is of `FilterUtils` type. It offers some useful utility functions for you to use in your filters.
+
+Labels assigned to articles are visible to your filters. You can, therefore, execute actions in your filtering script, based on which labels are assigned to the article. The property is called `assignedLabels` and is an array of the `Label` objects.
+
+Passed article also offers a special function:
+
+```js
+Boolean MessageObject.isAlreadyInDatabase(DuplicateCheck)
+```
+
+which allows you to perform runtime check for existence of the article in RSS Guard's database. Parameter is the value from enumeration `DuplicateCheck`. It specifies how exactly the article should match.
+
+For example, if you want to check if there is already another article by the same author in a database, you should call `msg.isAlreadyInDatabase(MessageObject.SameAuthor)`.  
+The values of enumeration can be combined in a single call with the [bitwise OR](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Bitwise_OR) (`|`) operator, like this:
+
+```js
+msg.isAlreadyInDatabase(MessageObject.SameAuthor | MessageObject.SameUrl)
+```
+
+## Class Reference Documentation
+
+Here is the reference of methods and properties of types available in your filtering scripts.
+
+### `MessageObject` class
+| Type      | Name(Parameters)              | Return value  | Read-only  | Synchronized  | Description
+| :---      | :---                          | :---          | :---:      | :---:         | ---
+| Property  | `assignedLabels`              | `Array<Label>`| ✅         | ✅            | List of labels assigned to the message/article.
+| Property  | `availableLabels`             | `Array<Label>`| ✅         | ❌            | List of labels which are currently available and can be assigned to the message. Available in RSS Guard 3.8.1+.
+| Property  | `feedCustomId`                | `String`      | ✅         | ❌            | Service-specific ID of the feed which this message belongs to.
+| Property  | `accountId`                   | `Number`      | ✅         | ❌            | RSS Guard's ID of the account activated in the program. This property is highly advanced, and you probably do not need to use it at all.
+| Property  | `id`                          | `Number`      | ✅         | ❌            | ID assigned to the message in RSS Guard local database.
+| Property  | `customId`                    | `String`      | ❌         | ❌            | ID of the message as provided by the remote service or feed file.
+| Property  | `title`                       | `String`      | ❌         | ❌            | The message title.
+| Property  | `url`                         | `String`      | ❌         | ❌            | The message URL.
+| Property  | `author`                      | `String`      | ❌         | ❌            | Author of the message.
+| Property  | `contents`                    | `String`      | ❌         | ❌            | Contents of the message.
+| Property  | `rawContents`                 | `String`      | ❌         | ❌            | This is the RAW contents of the message obtained from remote service/feed. A raw XML or JSON element data. This attribute has the value only if `runningFilterWhenFetching` returns `true`. In other words, this attribute is not persistently stored in the RSS Guard's DB. Also, this attribute is artificially filled in with ATOM-like data when testing the filter.
+| Property  | `score`                       | `Number`      | ❌         | ❌            | Arbitrary number in range \<0.0, 100.0\>. You can use this number to sort messages in a custom fashion as this attribute also has its own column in articles list.
+| Property  | `created`                     | `Date`        | ❌         | ❌            | Date/time of the message.
+| Property  | `isRead`                      | `Boolean`     | ❌         | ✅            | Is message read?
+| Property  | `isImportant`                 | `Boolean`     | ❌         | ✅            | Is message important?
+| Property  | `isDeleted`                   | `Boolean`     | ❌         | ❌            | Is message placed in recycle bin?
+| Method    | `addEnclosure(String url, String mime_type)` | `void` | ❌         | ❌            | Adds multimedia attachment to the article.
+| Method    | `isAlreadyInDatabase(DuplicateCheck criteria)` | `Boolean` | ❌         | ❌            | Allows you to check if message is already stored in the RSS Guard's DB. See possible parameters.
+| Method    | `findLabelId(String label_name)`         | `String`     | ❌         | ❌            | If you enter the label name, method returns label's `customId` which then can be used in `assignLabel()` and `deassignLabel` methods.
+| Method    | `assignLabel(String label_id)`         | `Boolean`     | ❌         | ❌            | Assigns label to the message. The `String` value is the `customId` property of `Label` type. See its API reference for relevant info.
+| Method    | `deassignLabel(String label_id)`       | `Boolean`     | ❌         | ❌            | Removes label from the message. The `String` value is the `customId` property of `Label` type. See its API reference for relevant info.
+| Method    | `createLabelId(String title, String color_hex_code)`       | `String`     | ❌         | ❌            | Creates the label with given name and given color hex code in form `#AABBCC`. Color can be omitted in which case auto-generated color is used.
+| Method    | `addEnclosure(String url, String mime_type)`       | `void`     | ❌         | ❌            | Appends new enclosure/attachment with given URL and MIME type to the article.
+| Property  | `runningFilterWhenFetching`   | `Boolean`     | ✅         | ❌            | Returns `true` if message filter is applied when message is fetched. Returns `false` if filter is applied manually, for example from **Article filters** window.<!-- TODO: is there another example when it's applied? should "for example" be dropped? -->
+
+### `Label` class
+| Type      | Name          | Return value  | Read-only | Description
+| :---      | :---          | :---          | :---:     | ---
+| Property  | `title`       | `String`      | ✅        | Label name.
+| Property  | `customId`    | `String`      | ✅        | Service-specific ID of the label. The ID is used as a unique identifier for label. It is useful if you want to assign/unassign the message label.
+| Property  | `color`       | `Color`       | ✅        | Label color. See the type `color` documentation in [Qt docs](https://doc.qt.io/qt-5/qml-color.html).
+
+### `FilteringAction` enum
+| Enumerant name    | Integer value | Description
+| :---              | :---          | ---
+| `Accept`          | 1             | Message is accepted and will be added or updated in DB.
+| `Ignore`          | 2             | Message is ignored and will **NOT** be added or updated in DB. Already existing message will not be purged from DB.
+| `Purge`           | 4             | Existing message is purged from the DB completely. Behaves like `Ignore` when there is a new incoming message.
+
+The `MessageObject` attributes are synchronized with service even if you return `Purge` or `Ignore`. In other words, even if the filter ignores the article, you can still tweak its properties, and they will be synchronized back to your server.
+
+### `DuplicateCheck` enum
+| Enumerant name    | Integer value | Description
+| :---              | :---          | ---
+| `SameTitle`       | 1             | Check if message has same title as some another messages.
+| `SameUrl`         | 2             | Check if message has same URL as some another messages.
+| `SameAuthor`      | 4             | Check if message has same author as some another messages.
+| `SameDateCreated` | 8             | Check if message has same date of creation as some another messages.
+| `AllFeedsSameAccount` | 16        | Perform the check across all feeds from your account, not just "current" feed.
+| `SameCustomId`    | 32            | Check if message with same custom ID exists in RSS Guard DB.
+
+### `utils` object
+| Type      | Name(Parameter)           | Return value  | How to call                               | Description
+| :---      | :---                      | :---          | :---                                      | ---
+| Method    | `hostname()`              | `String`      | `utils.hostname()`                        | Returns name of your PC.
+| Method    | `fromXmlToJson(String xml_string)`   | `String`      | `utils.fromXmlToJson('<h1>hello</h1>')`   | Converts XML string into JSON.
+| Method    | `parseDateTime(String date_time)`   | `Date`        | `utils.parseDateTime('2020-02-24T08:00:00')`  | Converts textual date/time representation into proper `Date` object.
+| Method    | `runExecutableGetOutput(String exec, String[] params)`   | `String`        | `utils.runExecutableGetOutput('cmd.exe', ['/c', 'dir'])`  | Launches external executable with optional parameters, reads its standard output, and returns the output when executable finishes.
+
+## Examples
+Accept only messages/articles with title containing "Series Name" or "Another series" in it (whitelist):
+```js
+var whitelist = [
+  'Series Name', 'Another series'
+];
+function filterMessage() {
+  if (whitelist.some(i => msg.title.indexOf(i) != -1)) {
+    return MessageObject.Accept;
+  } else {
+    return MessageObject.Ignore;
+  }
+}
+```
+
+Accept only messages/articles with title NOT containing "Other Series Name" or "Some other title" in it (blacklist):
+```js
+var blacklist = [
+  'Other Series Name', 'Some other title'
+];
+function filterMessage() {
+  if (blacklist.some(i => msg.title.indexOf(i) != -1)) {
+    return MessageObject.Ignore;
+  } else {
+    return MessageObject.Accept;
+  }
+}
+```
+
+Accept only messages/articles from "Bob", while also mark them important:
+```js
+function filterMessage() {
+  if (msg.author == "Bob") {
+    msg.isImportant = true;
+    return MessageObject.Accept;
+  }
+  else {
+    return MessageObject.Ignore;
+  }
+}
+```
+
+Replace all "dogs" with "cats"!
+```js
+function filterMessage() {
+  msg.title = msg.title.replace("dogs", "cats");
+  return MessageObject.Accept;
+}
+```
+
+Use published element instead of updated element (for `ATOM` entries only):
+```js
+function filterMessage() {
+  // Read raw contents of message and
+  // convert to JSON.
+  json = utils.fromXmlToJson(msg.rawContents);
+  jsonObj = JSON.parse(json)
+
+  // Read published date and parse it.
+  publishedDate = jsonObj.entry.published.__text;
+  parsedDate = utils.parseDateTime(publishedDate);
+
+  // Set new date/time for message and
+  // proceed.
+  msg.created = parsedDate;
+  return MessageObject.Accept;
+}
+```
+
+Dump RAW data of each message to RSS Guard debug output:
+```js
+function filterMessage() {
+  console.log(msg.rawContents);
+  return MessageObject.Accept;
+}
+```
+
+When running the above script for Tiny Tiny RSS, it produces the following debug output:
+```
+...
+time="    34.360" type="debug" -> feed-downloader: Hooking message took 4 microseconds.
+time="    34.361" type="debug" -> {"always_display_attachments":false,"attachments":[],"author":"Aleš Kapica","comments_count":0,"comments_link":"","content":"<p>\nNaposledy jsem psal o čuňačení v MediaWiki asi před půl rokem, kdy jsem chtěl upozornit na to, že jsem přepracoval svoji původní šablonu Images tak, aby bylo možné používat výřezy z obrázků a stránek generovaných z DjVu a PDF dokumentů. Blogpost nebyl nijak extra hodnocen, takže mě vcelku nepřekvapuje, jak se do hlavní vývojové větve MediaWiki dostávají čím dál větší prasečiny.\n</p>","feed_id":"5903","feed_title":"abclinuxu - blogy","flavor_image":"","flavor_stream":"","guid":"{\"ver\":2,\"uid\":\"52\",\"hash\":\"SHA1:5b49e4d8f612984889ba25e7834e80604c795ff8\"}","id":6958843,"is_updated":false,"labels":[],"lang":"","link":"http://www.abclinuxu.cz/blog/kenyho_stesky/2021/1/cunacime-v-mediawiki-responzivni-obsah-ii","marked":false,"note":null,"published":false,"score":0,"tags":[""],"title":"Čuňačíme v MediaWiki - responzivní obsah II.","unread":true,"updated":1610044674}
+time="    34.361" type="debug" -> feed-downloader: Running filter script, it took 348 microseconds.
+time="    34.361" type="debug" -> feed-downloader: Hooking message took 4 microseconds.
+time="    34.361" type="debug" -> {"always_display_attachments":false,"attachments":[],"author":"kol-ouch","comments_count":0,"comments_link":"","content":"Ahoj, 1. 6. se blíží, tak začínám řešit co s bambilionem fotek na google photos. \n<p class=\"separator\"></p>\nZa sebe můžu říct, že gp mi vyhovují - ne snad úplně tím, že jsou zadarmo, ale hlavně způsobem práce s fotkami, možnostmi vyhledávání v nich podle obsahu, vykopírování textu z nich, provázaností s mapami, recenzemi, možnostmi sdílení, automatickým seskupováním a podobně.","feed_id":"5903","feed_title":"abclinuxu - blogy","flavor_image":"","flavor_stream":"","guid":"{\"ver\":2,\"uid\":\"52\",\"hash\":\"SHA1:1277107408b159882b95ca7151a0ec0160a3971a\"}","id":6939327,"is_updated":false,"labels":[],"lang":"","link":"http://www.abclinuxu.cz/blog/Co_to_je/2021/1/kam-s-fotkama","marked":false,"note":null,"published":false,"score":0,"tags":[""],"title":"Kam s fotkama?","unread":true,"updated":1609750800}
+...
+```
+
+For `RSS 2.0` message, the result might look as follows:
+```
+...
+time="     3.568" type="debug" -> feed-downloader: Hooking message took 6 microseconds.
+time="     3.568" type="debug" -> <item>
+<title><![CDATA[Man Utd's Cavani 'not comfortable' in England, says father]]></title>
+<description><![CDATA[Manchester United striker Edinson Cavani "does not feel comfortable" and could move back to his native South America, his father said.]]></description>
+<link>https://www.bbc.co.uk/sport/football/56341983</link>
+<guid isPermaLink="true">https://www.bbc.co.uk/sport/football/56341983</guid>
+<pubDate>Tue, 09 Mar 2021 23:46:03 GMT</pubDate>
+</item>
+
+time="     3.568" type="debug" -> feed-downloader: Running filter script, it took 416 microseconds.
+...
+```
+
+Write details of available labels and assign the first label to the message:
+```js
+function filterMessage() {
+  console.log('Number of assigned labels: ' + msg.assignedLabels.length);
+  console.log('Number of available labels: ' + msg.availableLabels.length);
+
+  var i;
+  for (i = 0; i < msg.availableLabels.length; i++) {
+    var lbl = msg.availableLabels[i];
+
+    console.log('Available label:');
+    console.log('  Title: \'' + lbl.title + '\' ID: \'' + lbl.customId + '\'');
+  }
+
+  if (msg.availableLabels.length > 0) {
+    console.log('Assigning first label to message...');
+    msg.assignLabel(msg.availableLabels[0].customId);
+
+    console.log('Number of assigned labels ' + msg.assignedLabels.length);
+  }
+
+  console.log();
+  return MessageObject.Accept;
+}
+```
+
+Make sure that you receive only one message with particular URL across all your feeds, plugin/account-wide. All other messages with the same URL are subsequently ignored:
+```js
+function filterMessage() {
+  if (msg.isAlreadyInDatabase(MessageObject.SameUrl | MessageObject.AllFeedsSameAccount)) {
+    return MessageObject.Ignore;
+  }
+  else {
+    return MessageObject.Accept;
+  }
+}
+```
+
+Remove "ads" from messages received from Inoreader. Method simply removes `div` which contains the advertisement:
+```js
+function filterMessage() {
+  msg.contents = msg.contents.replace(/<div>\s*Ads[\S\s]+Remove<\/a>[\S\s]+adv\/www\/delivery[\S\s]+?<\/div>/im, '');
+
+  return MessageObject.Accept;
+}
+```
\ No newline at end of file
diff --git a/docs/source/features/gui-concepts.md b/docs/source/features/gui-concepts.md
new file mode 100644
index 000000000..8841a839b
--- /dev/null
+++ b/docs/source/features/gui-concepts.md
@@ -0,0 +1,27 @@
+General GUI Concepts & Manipulating Accounts & Adding Feeds
+===========================================================
+Feed list displays all your feeds and other items such as recycle bin.
+
+Article list displays all your articles depending on what is selected in feed list.
+
+Article preview displays details of selected article or information about selected item from feed list if no article is selected.
+
+Titlebar of RSS Guard display number of unread articles in square brackets.
+
+There are two toolbars available, separate toolbar for feed list and for article list.
+
+----
+
+When you start RSS Guard for the very first time, you are greeted with `Add account` dialog where you select which account you want to operate with. If you want to have classic `RSS/ATOM` feed reader, then select `RSS/RDF/ATOM/JSON` option.
+
+<img alt="alt-img" src="images/accounts.png">
+
+Each "account" offers account-specific actions which are accessible in relevant submenu.
+
+<img alt="alt-img" src="images/account-menu.png">
+
+To add new feed into the account you simply use `Feeds -> Add item -> Add a new feed` menu item.
+
+<img alt="alt-img" src="images/feed-details.png">
+
+In 99% of cases, you only need to insert feed URL into `Source` field and then hit `Fetch it now` button which will download feed metadata and fill all other boxes.
\ No newline at end of file
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index a27b43e4d..8ba7cf585 100644
--- a/docs/source/index.rst
+++ b/docs/source/index.rst
@@ -1,8 +1,8 @@
 RSS Guards documentation!
-=====================================
+=========================
 
 .. toctree::
-   :maxdepth: 2
+   :maxdepth: 1
 
    what
    donations
@@ -10,8 +10,16 @@ RSS Guards documentation!
    supported-os
    supported-readers
 
+.. toctree::
+   :maxdepth: 1
+   :caption: Features
+   :glob:
+
+   features/gui-concepts
+   features/*
+
 Indices and tables
-==================
+------------------
 
 * :ref:`genindex`
 * :ref:`modindex`
diff --git a/docs/source/requirements.txt b/docs/source/requirements.txt
index 787720e65..0bc2820eb 100644
--- a/docs/source/requirements.txt
+++ b/docs/source/requirements.txt
@@ -1,2 +1,3 @@
 myst_parser
+linkify-it-py
 sphinx-rtd-theme
\ No newline at end of file
diff --git a/docs/source/supported-os.md b/docs/source/supported-os.md
new file mode 100644
index 000000000..0241b5849
--- /dev/null
+++ b/docs/source/supported-os.md
@@ -0,0 +1,8 @@
+Supported Operating Systems
+===========================
+RSS Guard is a cross-platform application, and at this point it is known to work on:
+* Windows 7+
+* GNU/Linux (including PinePhone and other Linux-based phone operating systems)
+* BSD (FreeBSD, OpenBSD, NetBSD, etc.)
+* macOS 10.14+
+* OS/2 (ArcaOS, eComStation)
\ No newline at end of file
diff --git a/docs/source/supported-os.rst b/docs/source/supported-os.rst
deleted file mode 100644
index 424be3d63..000000000
--- a/docs/source/supported-os.rst
+++ /dev/null
@@ -1,9 +0,0 @@
-Supported Operating Systems
-===========================
-
-RSS Guard is a cross-platform application, and at this point it is known to work on:
- * Windows 7+
- * GNU/Linux (including PinePhone and other Linux-based phone operating systems)
- * BSD (FreeBSD, OpenBSD, NetBSD, etc.)
- * macOS 10.14+
- * OS/2 (ArcaOS, eComStation)
\ No newline at end of file
diff --git a/docs/source/supported-readers.md b/docs/source/supported-readers.md
new file mode 100644
index 000000000..56514d640
--- /dev/null
+++ b/docs/source/supported-readers.md
@@ -0,0 +1,29 @@
+Supported Feed Readers
+======================
+RSS Guard is multi-account application and supports many web-based feed readers via built-in plugins. One of the plugins, of course, provides the support for standard list of **RSS/ATOM/JSON** feeds with the set of features everyone would expect from classic feed reader.
+
+I organized the supported web-based feed readers into an elegant table:
+
+| Service | Two-way Synchronization | Intelligent Synchronization Algorithm (ISA) <sup>1</sup> | Synchronized Labels <sup>2</sup> <a id="sfrl"></a> | OAuth <sup>4</sup> |
+| :---              | :---:  | :---: | :---: | :---:
+| Feedly            | ✅ | ✅ | ✅ | ✅ (only for official binaries)
+| Gmail             | ✅ | ✅ | ✅ | ✅
+| Google Reader API <sup>3</sup> | ✅ | ✅ | ✅ | ✅ (only for Inoreader)
+| Nextcloud News    | ✅ | ❌ | ❌ | ❌
+| Tiny Tiny RSS     | ✅ | ✅ | ✅ | ❌
+
+<sup>1</sup> Some plugins support next-gen intelligent synchronization algorithm (ISA) which has some benefits, as it usually offers superior synchronization speed, and transfers much less data over your network connection.
+
+With ISA, RSS Guard only downloads articles which are new or were updated by remote server. The old algorithm usually always fetches all available articles, even if they are not needed, which leads to unnecessary overload of your network connection and the RSS Guard.
+
+<sup>2</sup> Note that labels are supported for all plugins, but for some plugins they are local-only, and are not synchronized with the service. Usually because service itself does not support the feature.
+
+<sup>3</sup> Tested services are:
+* Bazqux
+* FreshRSS
+* Inoreader
+* Miniflux
+* Reedah
+* TheOldReader
+
+<sup>4</sup> [OAuth](https://en.wikipedia.org/wiki/OAuth) is a secure way of authenticating users in online applications.
\ No newline at end of file
diff --git a/docs/source/supported-readers.rst b/docs/source/supported-readers.rst
deleted file mode 100644
index 20056ac07..000000000
--- a/docs/source/supported-readers.rst
+++ /dev/null
@@ -1,32 +0,0 @@
-Supported Feed Readers
-======================
-
-RSS Guard is multi-account application and supports many web-based feed readers via built-in plugins. One of the plugins, of course, provides the support for standard list of **RSS/ATOM/JSON** feeds with the set of features everyone would expect from classic feed reader.
-
-I organized the supported web-based feed readers into an elegant table:
-
-+-------------------+-------------------------+---------------------------------------+---------------------+-------+
-| Service           | Two-way Synchronization | Intelligent Synchronization Algorithm | Synchronized Labels | OAuth |
-+===================+=========================+=======================================+=====================+=======+
-| Feedly            | ✅                      | ✅                                    | ✅                  | ✅    |
-+-------------------+-------------------------+---------------------------------------+---------------------+-------+
-| Gmail             | ✅                      | ✅                                    | ✅                  | ✅    |
-+-------------------+-------------------------+---------------------------------------+---------------------+-------+
-| Google Reader API | ✅                      | ✅                                    | ✅                  | ✅    |
-+-------------------+-------------------------+---------------------------------------+---------------------+-------+
-| Nextcloud News    | ✅                      | ❌                                    | ❌                  | ❌    |
-+-------------------+-------------------------+---------------------------------------+---------------------+-------+
-| Tiny Tiny RSS     | ✅                      | ✅                                    | ✅                  | ❌    |
-+-------------------+-------------------------+---------------------------------------+---------------------+-------+
-
-:superscript:`1` Some plugins support next-gen intelligent synchronization algorithm which has some benefits, as it usually offers superior synchronization speed, and transfers much less data over your network connection. RSS Guard only downloads articles which are new or were updated by remote server. The old algorithm usually always fetches all available articles, even if they are not needed, which leads to unnecessary overload of your network connection and the RSS Guard.
-
-:superscript:`2` Note that labels are supported for all plugins, but for some plugins they are local-only, and are not synchronized with the service. Usually because service itself does not support the feature.
-
-:superscript:`3` Tested services are:
- * Bazqux
- * FreshRSS
- * Inoreader
- * Miniflux
- * Reedah
- * TheOldReader
\ No newline at end of file
diff --git a/docs/source/what.md b/docs/source/what.md
new file mode 100644
index 000000000..e88d4eb88
--- /dev/null
+++ b/docs/source/what.md
@@ -0,0 +1,3 @@
+What is RSS Guard?
+==================
+RSS Guard is an [open-source](https://en.wikipedia.org/wiki/Open_source) cross-platform multi-protocol desktop feed reader. It is able to fetch feeds in RSS/RDF/ATOM/JSON formats and connect to multiple web-based feed readers. RSS Guard is developed on top of the [Qt library](http://qt-project.org).
\ No newline at end of file
diff --git a/docs/source/what.rst b/docs/source/what.rst
deleted file mode 100644
index 2618e6479..000000000
--- a/docs/source/what.rst
+++ /dev/null
@@ -1,6 +0,0 @@
-:tocdepth: 2
-
-What is RSS Guard?
-==================
-
-RSS Guard is an `open-source <https://en.wikipedia.org/wiki/Open_source>`_ cross-platform multi-protocol desktop feed reader. It is able to fetch feeds in RSS/RDF/ATOM/JSON formats and connect to multiple web-based feed readers. RSS Guard is developed on top of the `Qt library <http://qt-project.org>`_.
\ No newline at end of file