Markdown
Markdown is a lightweight markup language for adding formatting elements to plain text. CLion recognizes Markdown files, provides a dedicated editor for them, and shows the rendered HTML in a live preview.
Create a new Markdown file
By default, CLion recognizes any file with the .md or .markdown extension as a Markdown file.
Right-click a directory in the Project tool window Alt+1 and select New | File.
Alternatively, you can select the necessary directory, press Alt+Insert, and then select File.
Enter a name for your file with a recognized extension, for example: readme.md.
The Markdown editor provides several basic formatting actions in the toolbar:
: Bold
: Strikethrough
: Italic
: Code
: Decrease heading level
: Increase heading level
: Convert an inline link to a reference link
You can use the preview pane to see the rendered HTML.
There is also completion for links to files in the current project, for example, if you need to reference source code, images, or other Markdown files.
Code blocks
To insert a fenced code block, use triple backticks (```) before and after the code block. If you specify the language for the code block, by default, the Markdown editor injects the corresponding language. This enables syntax highlighting and other coding assistance features for the specified language: code completion, inspections, and intention actions.
Disable coding assistance in code blocks
If your code blocks are not meant to be syntactically correct, you may want to disable code injection and syntax errors in code blocks.
In the Settings/Preferences dialog Ctrl+Alt+S, select Languages \& Frameworks | Markdown.
Configure the following options:
Disable automatic language injection in code fences Do not inject any coding assistance for code blocks. Hide errors in code fences Do not check the syntax for errors. Click OK to apply the changes.
Diagrams
The Markdown editor can render diagrams defined with Mermaid and PlantUML. This is disabled by default and requires the corresponding Markdown extensions.
Enable diagram support
In the Settings/Preferences dialog Ctrl+Alt+S, select Languages \& Frameworks | Markdown.
Enable either Mermaid or PlantUML under Markdown Extensions.
After CLion downloads the relevant extensions, click OK to apply the changes.
HTML preview
By default, the Markdown editor shows a preview pane next to it for rendered HTML code based on the Markdown file. You can use 
or 
in the top right corner of the Markdown editor to show only the editor or the preview pane.
The scrollbars in the editor and in the preview pane are synchronized, meaning that the location in the preview pane corresponds to the location in the source. To disable this, click 
in the top right corner of the Markdown editor.
To split the editor and preview pane horizontally (top and bottom) instead of the default vertical split, in the Settings/Preferences dialog Ctrl+Alt+S, select Languages \& Frameworks | Markdown, and then select Split horizontally under Editor and Preview Panel Layout.
Custom CSS
CLion provides default style sheets for rendering HTML in the preview pane. These style sheets were designed to be consistent with the default UI themes. You can configure specific CSS rules to make small presentation changes (for example, change the font size for headings or line spacing in lists) or you can provide an entirely new CSS to better match your expected output (for example, if you want to replicate the GitHub Markdown style).
In the Settings/Preferences dialog Ctrl+Alt+S, select Languages \& Frameworks | Markdown.
Configure the settings under Custom CSS:
Select Load from URI to specify the location of a custom CSS file.
Select Add CSS rules rules to enter specific CSS rules that you want to override.
Productivity tips
Navigate a large Markdown document
Customize the Markdown code style
In the Settings/Preferences dialog Ctrl+Alt+S, select Editor | Code Style | Markdown.
Select the color scheme, accept the highlighting settings inherited from defaults, or customize them as described in Colors and fonts.