Setting link colours on my Thank You page with CSS

On my Thank You page I have a Click Here to Download a Guide link. When I test it it appears in bright blue, the default colours on most browsers. I have added the following CSS in the Custom CSS box but it does not seem to be takign effect. I wanted to check if the format or code was correct:

 

a:link {

 color: #FFFFFF;

 background-color: transparent;

 text-decoration: underline;

}

a:visited {

 color: #FFFFFF;

 background-color: transparent;

 text-decoration: underline;

}

a:active {

 color: #FFFFFF;

 background-color: transparent;

 text-decoration: underline;

}

a:hover {

 color: #C9CCC9;

 background-color: transparent;

 text-decoration: underline;

}