Cross-Browser Details and Summary Tags
This feature is already supported by a few major browsers including Chrome, Safari and Opera.
You can use Details and Summary tags like this:
<details> <summary>Copyright 1999-2014.</summary> <p> - by Refsnes Data. All Rights Reserved.</p> <p>All content and graphics on this web site are the property of the company Refsnes Data.</p> </details>
More information can be found here.