Matches elements when the specified attribute is present. Variations on syntax allow you to target specific attribute values and include options for matching specific string values. While it’s not necessary to preface the attribute value with a simple selector, doing so allows you to match specific element types with attribute values.
Basic Syntax
Attributes are surrounded by left and right brackets ([ * ]). To target any element with a class attribute, for example, you would use [class]. To be more specific, you can add a element selector prior to the attribute with no whitespace. The selector div[class] would match any div elements with a class attribute, regardless of the value of the attribute.
[class] {
color: red;
}
div[class] {
color: red;
}