JSFiddle - React, Tailwind, and code Playground

HTML

<form>
    <input type="text" id="name" name="name" placeholder="Name" class="required" />
    <br/>
    <input type="text" id="email" name="email" placeholder="Email" />
    <br/>
    <input type="submit" />
</form>

CSS

.required::-webkit-input-placeholder:after {
    content:'*';
    color: red;
}
.required:-moz-placeholder:after {
    /* Firefox 18- */
    content:'*';
    color: red;
}
.required::-moz-placeholder:after {
    /* Firefox 19+ */
    content:'*';
    color: red;
}
.required:-ms-input-placeholder:after {
    content:'*';
    color: red;
}