对于同样的问题，我发现的最简单的解决方案是使用一个多行表，只有一行，没有标题(第一列是图像，第二列是文本):

----------------------- ------------------------------------
![Tip](images/tip.png)\ Table multiline text bla bla bla bla
                        bla bla bla bla bla bla bla ... the
                        blank line below is important 

----------------------------------------------------------------

另一种可能工作(PDF)的方法是使用Latex默认的fbox指令:

 \fbox{My text!}

或FancyBox模块获得更高级的功能(和更好看的盒子):http://www.ctan.org/tex-archive/macros/latex/contrib/fancybox。

使用GitHub，我通常会插入一个blockquote。

> **_NOTE:_**  The note content.

变得……

注:说明内容。

当然，总有简单的HTML…

使用警告扩展。对于mkdocs，可以在mkdocs中配置。yml文件:

markdown_extensions:
    - admonition

然后在md文件中插入注释，如下所示:

!!! note

     This is a note.

这里有一个例子。

类似于Etienne的解决方案，一个简单的表格格式很好:

| | |
|-|-|
|`NOTE` | This is something I want you to notice. It has a lot of text, and I want that text to wrap within a cell to the right of the `NOTE`, instead of under it.|

另一种选择(更强调)是将内容作为无主体表的头:

|`NOTE` | This is something I want you to notice. It has a lot of text, and I want that text to wrap within a cell to the right of the `NOTE`, instead of under it.|
|-|-|

最后，你可以添加一条水平线(主题断线)来创建一个封闭的方框(尽管线条样式与表中的标题行略有不同):

| | |
|-|-|
|`NOTE` | This is something I want you to notice. It has a lot of text, and I want that text to wrap within a cell to the right of the `NOTE`, instead of under it.|

---

注意文本后面的空行。

你试过使用双标签吗?做一个盒子:

Start on a fresh line
Hit tab twice, type up the content
Your content should appear in a box

它在带有html输出的常规Rmarkdown文档中为我工作。双选项卡部分应该出现在一个圆角矩形浅灰色框中。

截至2021年9月: 这里有一种方法建立一个文本框在markdown使用html div标签和类'warning'。它在Jupyter Notebook和Typora上工作得很好。 您可以修改背景和字体颜色。

<div class="warning" style='padding:0.1em; background-color:#E9D8FD; color:#69337A'>
<span>
<p style='margin-top:1em; text-align:center'>
<b>On the importance of sentence length</b></p>
<p style='margin-left:1em;'>
This sentence has five words. Here are five more words. Five-word sentences are fine. But several together bocome monotonous. Listen to what is happening. The writing is getting boring. The sound of it drones. It's like a stuck record. The ear demands some variety.<br><br>
    Now listen. I vary the sentence length, and I create music. Music. The writing sings. It has a pleasent rhythm, a lilt, a harmony. I use short sentences. And I use sentences of medium length. And sometimes when I am certain the reader is rested, I will engage him with a sentence of considerable length, a sentence that burns with energy and builds with all the impetus of a crescendo, the roll of the drums, the crash of the cymbals -- sounds that say listen to this, it is important.
</p>
<p style='margin-bottom:1em; margin-right:1em; text-align:right; font-family:Georgia'> <b>- Gary Provost</b> <i>(100 Ways to Improve Your Writing, 1985)</i>
</p></span>
</div>

或者(在设计上增加一点——圆角和边框)

<div class="warning" style='background-color:#E9D8FD; color: #69337A; border-left: solid #805AD5 4px; border-radius: 4px; padding:0.7em;'>
<span>
<p style='margin-top:1em; text-align:center'>
<b>On the importance of sentence length</b></p>
<p style='margin-left:1em;'>
This sentence has five words. Here are five more words. Five-word sentences are fine. But several together bocome monotonous. Listen to what is happening. The writing is getting boring. The sound of it drones. It's like a stuck record. The ear demands some variety.<br><br>
    Now listen. I vary the sentence length, and I create music. Music. The writing sings. It has a pleasent rhythm, a lilt, a harmony. I use short sentences. And I use sentences of medium length. And sometimes when I am certain the reader is rested, I will engage him with a sentence of considerable length, a sentence that burns with energy and builds with all the impetus of a crescendo, the roll of the drums, the crash of the cymbals -- sounds that say listen to this, it is important.
</p>
<p style='margin-bottom:1em; margin-right:1em; text-align:right; font-family:Georgia'> <b>- Gary Provost</b> <i>(100 Ways to Improve Your Writing, 1985)</i>
</p></span>
</div>