Template:Showhide box

Usage
You need to include header=, and content=. Just fill in the information after the = signs. Header is what will be in the "always show" part of the box. Content will be the part that will have a button to be hidden. Header and content are capitalization sensitive and must be all lowercase.

Additionally, you can SUBST: this template so you can add style parameters afterwards. This is more advanced, and will clutter up a page with many SUBST:'d boxes quickly with code.