JSFiddle - React, Tailwind, and code Playground

HTML

<div class="input-block important error" error-msg="Invalid email">
  <input class="field email" type="email" name="email" required="required">
</div>

CSS

.input-block {
    display: flex;
    width: 100%;
    max-width: 440px;
    height: 40px;
    margin: 0 auto 60px;
    border-bottom: 1px solid #666666;
    color: #999999;
    box-sizing: border-box;
 }
    
    .input-block .field {
    height: 35px;
    width: 100%;
    border: none;
    color: #000;
    font-size: 16px;
    outline: none;
    resize: none;
}