JSFiddle - React, Tailwind, and code Playground

HTML

<header>
    <hgroup>
        <h1><span>GUITARRA</span></h1>
        <h2>Profesor</h2>
    </hgroup>
</header>

CSS

header h1 span{
    font-size: 42px;
    margin: 0;
    padding:0;
    border-bottom: 3px solid red; 
    line-height: 10px;

}