Thursday, August 27, 2026

Case Insensitive CSS Attribute Selector


CSS selectors never cease to amaze me in how powerful they can be in matching complex patterns. Most of that flexibility is in parent/child/sibling relationships, very seldomly in value matching. Consider my surprise when I learned that CSS allows matching attribute values regardless off case!

Adding a {space}i to the attribute selector brackets will make the attribute value search case insensitive:

/* case sensitive, only matches "example" */
[class=example] {
  background: pink;
}

/* case insensitive, matches "example", "eXampLe", etc. */
[class=example i] {
  background: lightblue;
}

The use cases for this i flag are likely very limited, especially if this flag is knew knowledge for you and you’re used to a standard lower-case standard. A loose CSS classname standard will have and would continue to lead to problems, so use this case insensitivity flag sparingly!

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