I'm trying to increase the font size of a link using a class but does not seem to work for me.

.style1 {font-size: 16px}

I'm trying to increase the link size from within the cms im using.

The html

<a href="[~[+id+]~]" title="[+title+]" class="style1">[+title+]</a>

Probably specificity.

The style may be getting overruled by a more specific CSS rule being applied.

Got it I was editing a copy of the file so the right one was not being edited woops

You need to specify the class in the css:

<style type='text/css'>
.style1 a {
    font: bold 13px sans-serif;
    color:#333;
    text-decoration: none;
}
.style1 a:hover { 
    color: #049;
}
.style1 a:active {
}
</style>

Then your HTML should look like this:

<a class='style1' href='#'></a>