Links should always be in the form:

<a href="link_url_here">Link text here</a>.

Never show the reader the URL; keep it within a word or sentence. 

So: 

For CERN's style guide for web texts, click here.

NOT

For CERN's style guide for web texts, click here: https://test-static-04.web.cern.ch

It may seem obvious, but check that the link is relevant, and always double-check that links are working before publishing.