JSFiddle - React, Tailwind, and code Playground
HTML
<label class="form-required">
<span>Last Name</span>
<input type="text" name="lastname">
</label>
CSS
.form-required > span:after {
content: " * ";
color: red;
}
<label class="form-required">
<span>Last Name</span>
<input type="text" name="lastname">
</label>
.form-required > span:after {
content: " * ";
color: red;
}