Option 1

display: table;

• no parent required

h1 {
    display: table; /* keep the background color wrapped tight */
    margin: 0px auto 0px auto; /* keep the table centered */
    padding:5px;font-size:20px;background-color:green;color:#ffffff;
}

<h1>The Last Will and Testament of Eric Jones</h1>

fiddle

http://jsfiddle.net/J7VBV/293/

more

display: table tells the element to behave as a normal HTML table would.

More about it at w3schools, CSS Tricks and here

Option 2

display: inline-flex;

• requires text-align: center; on parent

.container {
    text-align: center; /* center the child */
}
h1 {
    display: inline-flex; /* keep the background color wrapped tight */
    padding:5px;font-size:20px;background-color:green;color:#ffffff;
}

<div class="container">
  <h1>The Last Will and Testament of Eric Jones</h1>
</div>

Option 3

display: flex;

• requires a flex parent container

.container {
  display: flex;
  justify-content: center; /* center the child */
}
h1 {
    display: flex;
    /* margin: 0 auto; or use auto left/right margin instead of justify-content center */
    padding:5px;font-size:20px;background-color:green;color:#ffffff;
}

    <div class="container">
      <h1>The Last Will and Testament of Eric Jones</h1>
    </div>

about

Probably the most popular guide to Flexbox and one I reference constantly is at CSS Tricks

Option 4

display: block;

• requires a flex parent container

.container {
  display: flex;
  justify-content: center; /* centers child */
}
h1 {
    display: block;
    padding:5px;font-size:20px;background-color:green;color:#ffffff;
}

<div class="container">
  <h1>The Last Will and Testament of Eric Jones</h1>
</div>

Option 5

::before

• requires entering words in css file (not very practical)

h1 {
    display: flex; /* set a flex box */
    justify-content: center; /* so you can center the content like this */
}

h1::before {
    content:'The Last Will and Testament of Eric Jones'; /* the content */
    padding: 5px;font-size: 20px;background-color: green;color: #ffffff;
}

<h1></h1>

fiddle

http://jsfiddle.net/J7VBV/457/

about

More about css pseudo elements ::before and ::after at CSS Tricks and pseudo elements in general at w3schools

Option 6

display: inline-block;

• centering with position: absolute and translateX

• requires a position: relative parent

.container {
  position: relative; /* required for absolute positioned child */
}
h1 {
  display: inline-block; /* keeps container wrapped tight to content */
  position: absolute; /* to absolutely position element */
  top: 0;
  left: 50%; /* part1 of centering with translateX/Y */
  transform: translateX(-50%); /* part2 of centering with translateX/Y */
  white-space: nowrap; /* text lines will collapse without this */
  padding:5px;font-size:20px;background-color:green;color:#ffffff;
}

  <h1>The Last Will and Testament of Eric Jones</h1>

about

More on centering with transform: translate(); (and centering in general) in this CSS tricks article

Option 7

text-shadow: and box-shadow:

• not what the OP was looking for but maybe helpful to others finding their way here.

h1, h2, h3, h4, h5 {display: table;margin: 10px auto;padding: 5px;font-size: 20px;color: #ffffff;overflow:hidden;}
h1 {
    text-shadow: 0 0 5px green,0 0 5px green,
                 0 0 5px green,0 0 5px green,
                 0 0 5px green,0 0 5px green,
                 0 0 5px green,0 0 5px green;
}
h2 {
    text-shadow: -5px -5px 5px green,-5px 5px 5px green,
                  5px -5px 5px green,5px 5px 5px green;
}
h3 {
    color: hsla(0, 0%, 100%, 0.8);
    text-shadow: 0 0 10px hsla(120, 100%, 25%, 0.5),
                 0 0 10px hsla(120, 100%, 25%, 0.5),
                 0 0 10px hsla(120, 100%, 25%, 0.5),
                 0 0 5px hsla(120, 100%, 25%, 1),
                 0 0 5px hsla(120, 100%, 25%, 1),
                 0 0 5px hsla(120, 100%, 25%, 1);
}
h4 { /* overflow:hidden is the key to this one */
    text-shadow: 0px 0px 35px green,0px 0px 35px green,
                 0px 0px 35px green,0px 0px 35px green;
}
h5 { /* set the spread value to something larger than you'll need to use as I don't believe percentage values are accepted */
  box-shadow: inset 0px 0px 0px 1000px green;
}

<h1>The First Will and Testament of Eric Jones</h1>
<h2>The 2nd Will and Testament of Eric Jones</h2>
<h3>The 3rd Will and Testament of Eric Jones</h3>
<h4>The Last Will and Testament of Eric Jones</h4>
<h5>The Last Box and Shadow of Eric Jones</h5>

fiddle

https://jsfiddle.net/Hastig/t8L9Ly8o/

More Options

There are a few other ways to go about this by combining the different display options and centering methods above.

I know this question has been answered very extensively. But not what I wanted or thought was the question based on the title. Therefore if others get in here looking for a possibility for colouring behind a word than this snippet is much easier:

\colorbox{blue!30}{blue}

or

\textcolor{blue!30}{blue}

resulting in:

This is possible by only adding \usepackage{xcolor}. Just some extra info :)

Colour Several Lines It is correct that the above methods does not work for several lines, if you to be more than one line you can do:

{\color{green} the text you want to write}

This can however also be wrapped in a function so it is easier to use several places during edits, e.g., for colouring new text or whatever:

\newcommand{\added}[1]{{\color{green}[added]:#1}}