<style type="text/css">
p.class1 {
    line-height: 2.5em;
}
p.class2 {
    line-height: 50px;
}
p.class3 {
    line-height: 300%;
}
</style>
<p>Here is some content <br /> and more <br /> and more</p>
<hr />
<p class="class1">Here is some content <br /> and more <br /> and more</p>
<hr />
<p class="class2">Here is some content <br /> and more <br /> and more</p>
<hr />
<p class="class3">Here is some content <br /> and more <br /> and more</p>