In angularjs\styles\angularjs.less:

Starting from Atom v1.13.0, the contents of atom-text-editor elements are no longer encapsulated within a shadow DOM boundary. This means you should stop using :host and ::shadow pseudo-selectors, and prepend all your syntax selectors with syntax--. To prevent breakage with existing style sheets, Atom will automatically upgrade the following selectors:

• atom-text-editor .entity.name.tag.block.any.html.angular, atom-text-editor::shadow .entity.name.tag.block.any.html.angular, atom-text-editor .entity.other.attribute-name.html.angular, atom-text-editor::shadow .entity.other.attribute-name.html.angular => atom-text-editor .entity.name.tag.block.any.html.angular, atom-text-editor.editor .syntax--entity.syntax--name.syntax--tag.syntax--block.syntax--any.syntax--html.syntax--angular, atom-text-editor .entity.other.attribute-name.html.angular, atom-text-editor.editor .syntax--entity.syntax--other.syntax--attribute-name.syntax--html.syntax--angular

• atom-text-editor .punctuation.definition.block.begin.angular, atom-text-editor::shadow .punctuation.definition.block.begin.angular, atom-text-editor .punctuation.definition.block.end.angular, atom-text-editor::shadow .punctuation.definition.block.end.angular => atom-text-editor .punctuation.definition.block.begin.angular, atom-text-editor.editor .syntax--punctuation.syntax--definition.syntax--block.syntax--begin.syntax--angular, atom-text-editor .punctuation.definition.block.end.angular, atom-text-editor.editor .syntax--punctuation.syntax--definition.syntax--block.syntax--end.syntax--angular

Automatic translation of selectors will be removed in a few release cycles to minimize startup time. Please, make sure to upgrade the above selectors as soon as possible.