docs: add tutorial and example for new features

_posts/2019-08-08-write-a-new-post.md

@@ -7,7 +7,7 @@ tags: [writing]
 render_with_liquid: false
 ---
 
-This post will guide you how to write a post on _Chirpy_ theme. Even if you have previous experience with Jekyll, this article is worth reading, because many features require specific variables to be set.
+This tutorial will guide you how to write a post in the _Chirpy_ template, and it's worth reading even if you've used Jekyll before, as many features require specific variables to be set.
 
 ## Naming and Path
 
@@ -177,9 +177,18 @@ By default, the image is centered, but you can specify the position by using one
   ```
   {: .nolineno}
 
+### Dark/Light mode
+
+You can make images follow theme preferences in dark/light mode. This requires you to prepare two images, one for dark mode and one for light mode, and then assign them a specific class (`dark` or `light`):
+
+```markdown
+![Light mode only](/path/to/light-mode.png){: .light }
+![Dark mode only](/path/to/dark-mode.png){: .dark }
+```
+
 ### Shadow
 
-The screenshots of the program window can be considered to show the shadow effect, and the shadow will be visible in the `light` mode:
+The screenshots of the program window can be considered to show the shadow effect:
 
 ```markdown
 ![Desktop View](/assets/img/sample/mockup.png){: .shadow }
@@ -209,7 +218,7 @@ The parsing result will automatically add the CDN prefix `https://cdn.com` befor
 ```html
 <img src="https://cdn.com/path/to/flower.png" alt="The flower">
 ```
-{: .nolineno}
+{: .nolineno }
 
 ### Image Path
 
@@ -220,7 +229,6 @@ When a post contains many images, it will be a time-consuming task to repeatedly
 img_path: /img/path/
 ---
 ```
-{: .nolineno }
 
 And then, the image source of Markdown can write the file name directly:
 
@@ -238,28 +246,49 @@ The output will be:
 
 ### Preview Image
 
-If you want to add an image to the top of the post contents, specify the attribute `path`, `width`, `height`, and `alt` for the image:
+If you want to add an image at the top of the article, please provide an image with a resolution of `1200 x 630`. Please note that if the image aspect ratio does not meet `1.91 : 1`, the image will be scaled and cropped.
+
+Knowing these prerequisites, you can start setting the image's attribute:
 
 ```yaml
 ---
 image:
   path: /path/to/image
-  width: 1000   # in pixels
-  height: 400   # in pixels
   alt: image alternative text
 ---
 ```
 
-Except for `alt`, all other options are necessary, especially the `width` and `height`, which are related to user experience and web page loading performance. The above section "[Size](#size)" also mentions this.
-
 Starting from _Chirpy v5.0.0_, the attributes `height` and `width` can be abbreviated: `height` → `h`, `width` → `w`. In addition, the [`img_path`](#image-path) can also be passed to the preview image, that is, when it has been set, the  attribute `path` only needs the image file name.
 
 For simple use, you can also just use `image` to define the path.
 
 ```yml
+---
 image: /path/to/image
+---
 ```
 
+### LQIP
+
+For preview images:
+
+```yaml
+---
+image:
+  lqip: /path/to/lqip-file # or base64 URI
+---
+```
+
+> You can observe LQIP in the preview image of post [_Text and Typography_](/posts/text-and-typography/).
+
+
+For normal images:
+
+```markdown
+![Image description](/path/to/image){: lqip="/path/to/lqip-file" }
+```
+{: .nolineno }
+
 ## Pinned Posts
 
 You can pin one or more posts to the top of the home page, and the fixed posts are sorted in reverse order according to their release date. Enable by:
@@ -357,6 +386,24 @@ If you want to display the **Liquid** snippet, surround the liquid code with `{%
 
 Or adding `render_with_liquid: false` (Requires Jekyll 4.0 or higher) to the post's YAML block.
 
+## Videos
+
+You can embed a video with the following syntax:
+
+```liquid
+{% include embed/{Platform}.html id='{ID}' %}
+```
+Where `Platform` is the lowercase of the platform name, and `ID` is the video ID.
+
+The following table shows how to get the two parameters we need in a given video URL, and you can also know the currently supported video platforms.
+
+| Video URL                                                                                          | Platform  | ID            |
+|----------------------------------------------------------------------------------------------------|-----------|:--------------|
+| [https://www.**youtube**.com/watch?v=**H-B46URT4mg**](https://www.youtube.com/watch?v=H-B46URT4mg) | `youtube` | `H-B46URT4mg` |
+| [https://www.**twitch**.tv/videos/**1634779211**](https://www.twitch.tv/videos/1634779211)         | `twitch`  | `1634779211`  |
+
+
+
 ## Learn More
 
 For more knowledge about Jekyll posts, visit the [Jekyll Docs: Posts](https://jekyllrb.com/docs/posts/).