JSFiddle - React, Tailwind, and code Playground

HTML

<h1>Neue <span>Infrastruktur</span> bequem im <span>Selbstbau</span></h1>

CSS

h1 span {
font-size: 3rem;
position: relative;
}

h1 span:nth-child(-n+2):before {
content: "";
position: absolute;
background-color: lightgreen;
top: 35px;
width: 100%;
height: 20px;
z-index: -1;
}