If the element is not rendered successfully, the text equivalent will be displayed.
For the <img> tags, we could use ALT attributes to represent the text equivalents. But things get complicated when the image is rendered as <span> + background-image css property. Since ALT attribute is only meaningful for <img>, it couldn’t be used here.
What should I do to create text equivalent for them?
You can use the
titleattribute.See this and this for details.