How to change the Label color while click input field

[KAVIN C]

I tried this css:
.my-phone-input:focus + .special-label {
color: blue;
}

[David Hernandez]

<div class="control-group">
    <label class="control-label" for="inputEmail">Firstname</label>
    <div class="controls">
        <input type="text" id="inputEmail" placeholder="Firstname">
    </div>
</div>

.control-group:has(input:focus) label{
 color: red;
}

You can check this post: On input focus change color of label. How?