JSFiddle - React, Tailwind, and code Playground

HTML

<form action="#" class="contact-us-form">
  <input type="text" placeholder="First Name" required>
  <input type="text" placeholder="Last name">
  <input type="email" placeholder="Email" required>
  <button onclick="myFunction()">Click me</button>
</form>
<p id="demo"></p>

SCSS

.contact-us-form {
  display: flex;
  padding-bottom: 1.25em;
  flex-direction: column;

  .text-field {
    margin: 0.5em;
  }
  .button-submit {
    margin: 1em;
    width: 100px;
    float: right;
  }

  input[type="text"],
  input[type="email"] {
    margin: 0.5em;
    height: 2em;
    min-width: 125px;
    border: 1px solid #eee;
    border-left: 3px solid;
    border-radius: 4px;
    transition: border-color 0.5s ease-out;

    &:optional {
      border-left-color: #999;
    }
    &:required {
      border-left-color: red;
    }
    &:invalid {
      border-left-color: salmon;
    }
  }
}

JavaScript

function myFunction() {
  document.getElementById("demo").innerHTML = "Hello World";
}