Images On AO3 - Tumblr Posts
Seconding this, but also adding that it's very helpful to both PC and mobile users to set the image size to scale with the browser if you're using image links.
<img src="insert image url here" width="75%"> is a good way to do it (note the percentage used for the width).
If you do it this way, the image will always scale to 75% (in this case) of the width of the text area, no matter how large or small the browser window is. 75% is what I personally recommend, but for taller images, it's better to use something around 50%. Use "preview" to check how it looks.
I feel the need to tell you that you can insert images into ao3 via certain html commands. You can also have hyperlinks.
<img src=”insert image url here”>
Oh thank you for letting me know! May have to edit the fic to do this when I have time