xxxxxxxxxx
<style>
mark {
background-color: yellow;
color: black;
}
</style>
<mark>Highlighted text!!</mark>
xxxxxxxxxx
<style>
h1 mark {
background-color: cyan (add any color you want);
}
</style>
<h1>
<mark>
And Voila! Cyan highlights!
</mark>
</h1>