Remplissez le texte de la couleur behid en html
Put the text in an inline element, such as a <span>.
<h1><span>The Last Will and Testament of Eric Jones</span></h1>
And then apply the background color on the inline element.
h1 {
text-align: center;
}
h1 span {
background-color: green;
}
An inline element is as big as its contents is, so that should do it for you.
Ankur