add debug theme for new macOS

Author: abnerlee

_posts/basic/2016-09-26-About Themes.md

@@ -67,5 +67,5 @@ Please see [Write Custom Theme for Typora](http://theme.typora.io/doc/Write-Cust
 
 You can open Chrome/Safari DevTools to debug element styles.
 
-- On macOS, you could check `Help` -> `Enable Debug` menu item, then right click anywhere in Typora's hybrid edit view, then click "Inspect Elements" from context menu.
+- On macOS, please follow <https://support.apple.com/en-hk/guide/safari/sfri20948/mac> to enable `Develop` menu from Safari, then inspect Typora's webview from Safari menu → Develop → [your macOS device name] → Typora.
 - On Windows/Linux, you could open DevTools from `View` -> `Toggle DevTools` menu item.

_posts/basic/2021-04-20-Export.md

@@ -376,9 +376,9 @@ You can export to EPUB file via `Export` → `Epub` from menu bar. You can confi
 
 You can set custom css from preferences panel, if you don’t know how to start with, you could check https://github.com/mattharrison/epub-css-starter-kit to make your own css style.
 
-#### Chapter Level
+#### Chapter Level in Outline
 
-Specify the heading level at which to split the EPUB into separate “chapter” files. The default is to split into chapters at level-1 headings. This option only affects the internal composition of the EPUB, not the way chapters and sections are displayed to users. Some readers may be slow if the chapter files are too large, so for large documents with few level-1 headings, one might want to use a chapter level of 2 or 3.
+Specify the number of section levels to include in the table of contents. The default is 3 (which means that level-1, 2, and 3 headings will be listed in the contents).
 
 #### Cover Image
 

_posts/how-to/2024-05-15-Debug Themes.md

@@ -0,0 +1,28 @@
+---
+layout: post
+title: Debug Themes / CSS
+date: 2024-05-15
+category: how-to
+author: typora.io
+tags: [style]
+typora-root-url: ../../
+typora-copy-images-to: ../../media/debug-themes
+---
+
+## macOS
+
+For macOS ≥ 13.3 and Typora ≥ 1.9, you can debug. Typora theme CSS in following way:
+
+1. **Enable Develop menu item in Safari** --- you must also have enabled Web Inspector in the Settings app under **Safari** > **Advanced** > **Web Inspector**. [Learn more about enabling Web Inspector…](https://webkit.org/web-inspector/enabling-web-inspector/)
+2. Select **Safari** menu → **Develop** → [your device name] → **Typora** to open the DevTools.
+
+<img src="/media/debug-themes/Screenshot 2024-05-15 at 18.31.36.png" alt="Screenshot 2024-05-15 at 18.31.36" style="zoom:50%;" />
+
+<img src="/media/debug-themes/Screenshot 2024-05-15 at 18.32.38.png" alt="Screenshot 2024-05-15 at 18.32.38" style="zoom:50%;" />
+
+For older macOS, you can enable debug mode from Typora preferences panel → General, restart Typora and then right click on Typora writing area and select *Inspect Element*.
+
+## Windows / Linux
+
+You could open DevTools from `View` -> `Toggle DevTools` menu item.
+