Line break (like <br>) using only css

Is it possible in pure css, that is without adding additional html tags, to make a line break like <br>? I want the line break after the <h4> element, but not before:

HTML

<li>
  Text, text, text, text, text. <h4>Sub header</h4>
  Text, text, text, text, text.
</li>

CSS

h4 {
  display: inline;
}

I have found many questions like this, but always with answers like "use display: block;", which I can't do, when the <h4> must stay on the same line.

It works like this:

h4 {
    display:inline;
}
h4:after {
    content:"\a";
    white-space: pre;
}

Example: http://jsfiddle.net/Bb2d7/

The trick comes from here: https://stackoverflow.com/a/66000/509752 (to have more explanation)

Try

h4{ display:block;}

in your css

http://jsfiddle.net/ZrJP6/

You can use ::after to create a 0px-height block after the <h4>, which effectively moves anything after the <h4> to the next line:

h4 {
  display: inline;
}
h4::after {
  content: "";
  display: block;
}

<ul>
  <li>
    Text, text, text, text, text. <h4>Sub header</h4>
    Text, text, text, text, text.
  </li>
</ul>

I know I'm late to the party but here's my two cents.

CSS

li h4 {
   break-after: always;
}

li h4::after {
   display: block;
   content: " ";
}