When you try to heart images using the bookmarklet some images may not get the pink border, which means they can't be hearted.
To be hearted an image must meet all the requirements below:
1. a width that is greater than or equal to 240 pixels
2. a height that is greater than or equal to 200 pixels
3. a valid image extension (jpg, png, gif)
Even if the width is bigger than 240px but the height is not, it will not get the pink border on the site.
If no valid images are found on the page you'll see an alert window saying that no images were found.
