Adding an i (or I) before the closing bracket in an attribute selector causes the value to be compared case-insensitively.

posted on 27.11.2020

<button class="mybutton">Send</button> <!-- red border -->
<button class="myButton">Send</button> <!-- green border -->

[class*="button" i] { /* matches mybutton and myButton */
  border: 10px solid green;
}

[class*="button"] { /* matches only mybutton */
  border-color: red;
}