Cannot use 'Float' property in custom popup content?

[FranklinAlexander]

I am trying to create custom content for a popup and I need to wrap text around an image. To do this, I am trying to add a 'float' property to the image style, but it is apparently being removed when I close the Arcade editor. I know my syntax is correct and it is not a typo, so is this just something that Esri does not allow? 

Here is my code:

<p style='font-size:1.15em'><b>Species Name</b></p>
<div>
  <img src='<img url>' style='width:40%; margin-right:20px; float:left;'>
  <p>Descriptive sentence</p>
</div>

The other style properties are working so this is very frustrating. As you can see from the images below, the float property is not being applied.

This is how it should look after applying the float property in the console:

Can someone please let me know what I am missing?