< and > are special characters in html. To display them literally you can use entities: &lt; and &gt; i.e. &lt;80 will result in <80. For a list of possible entities you can scout the web, e.g. here.

Hi and welcome to devnet, What about painting a partially transparent rectangle over the part of the text that should be highlighted ? You could draw the text first and then the rectangle over. Hope it helps