Something hiding inside here - credit to CynthiaShin Lee

So today I'm going to teach you guys how to do this , this will make your blog look more tie and clean . So let start it ,

1st : Dashboard - Design - Add gadget - HTML/JavaScript ( copy and paste this code in HTML/JavaScript )

2nd :

<div id="spoiler" style="display: none;">
Write anything in here.</div>
<button onclick="if(document.getElementById('spoiler') .style.display=='none') {document.getElementById('spoiler') .style.display=''}else{document.getElementById('spoiler') .style.display='none'}" title="Click to show/hide content" type="button">Click Here</button>

3rd : Done and save ,

- credit to CynthiaShin Lee