fill color behid text in html

1Put the text in an inline element, such as a <span>.
2
3<h1><span>The Last Will and Testament of Eric Jones</span></h1>
4And then apply the background color on the inline element.
5
6h1 {
7    text-align: center; 
8}
9h1 span { 
10    background-color: green; 
11}
12An inline element is as big as its contents is, so that should do it for you.

1Option 1
2display: table;
3
4no parent required
5h1 {
6    display: table; /* keep the background color wrapped tight */
7    margin: 0px auto 0px auto; /* keep the table centered */
8    padding:5px;font-size:20px;background-color:green;color:#ffffff;
9}
10<h1>The Last Will and Testament of Eric Jones</h1>