[attr]

Represents an element with an attribute name of attr.

[attr="value"]

Represents an element with an attribute name of attr and whose value is exactly "value".

[attr~="value"]

Represents an element with an attribute name of attr whose value is a whitespace-separated list of words, one of which is exactly "value".

[attr|="value"]

Represents an element with an attribute name of attr. Its value can be exactly “value” or can begin with “value” immediately followed by “-” (U+002D). It can be used for language subcode matches.

[attr^="value"]

Represents an element with an attribute name of attr and whose first value is prefixed by "value".

[attr$="value"]

Represents an element with an attribute name of attr and whose last value is suffixed by "value".

[attr*="value"]

Represents an element with an attribute name of attr and whose value contains at least one occurrence of string "value" as substring.

[attr "operator value" i]

Adding an i (or I) before the closing bracket causes the value to be compared case-insensitively (for characters within the ASCII range).

Learn more at: Attribute selectors - CSS or CSS-Specification