<a href="https://github.com/jrblevin/markdown-mode/pull/706" class="autolinkedURL autolinkedURL-url" target="_blank">github.com/jrblevin/markdown-mode/pull/706</a>
I implemented <code>markdown-fontify-whole-heading-line</code> flag. This is similar to <code>org-fontify-whole-heading-line</code> flag in org-mode. If this variable is non-nil, markdown-mode sets face properties for whole header lines.
So you can highlight whole lines for headers by setting <code>background</code> and <code>extend</code> properties of <code>markdown-header-face-*</code>.
For example
<pre><code class="lang-lisp">(setq markdown-fontify-whole-heading-line t)
(set-face-attribute 'markdown-header-face-1 nil :extend t :background "green" :foreground "black")
(set-face-attribute 'markdown-header-face-2 nil :extend t :background "pink" :foreground "black")
</code></pre>
then markdown-mode highlights as below
<img src="https://cdn.hashnode.com/res/hashnode/image/upload/v1652021834161/6heJn0TcZ.png" alt="markdown-mode.png" />

https://github.com/jrblevin/markdown-mode/pull/706

I implemented `markdown-fontify-whole-heading-line` flag. This is similar to `org-fontify-whole-heading-line` flag in org-mode. If this variable is non-nil, markdown-mode sets face properties for whole header lines.

So you can highlight whole lines for headers by setting `background` and `extend` properties of `markdown-header-face-*`.

For example

```lisp
(setq markdown-fontify-whole-heading-line t)
(set-face-attribute 'markdown-header-face-1 nil :extend t :background "green" :foreground "black")
(set-face-attribute 'markdown-header-face-2 nil :extend t :background "pink" :foreground "black")
```

then markdown-mode highlights as below


![markdown-mode.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1652021834161/6heJn0TcZ.png align="left")



Highlight whole line for markdown headers