Why do WYSIWYG editors strip out certain HTML, Javascript and style information?
TinyMCE and most other WYSIWYG (what you see is what you get) editors strip out ‘unrecognised’ html tags and attributes. Essentially it is a primitive attempt at a security feature that assumes that either you don’t know what you are doing or that you are an untrusted entity. This results in the editor trying to second guess your actions. Some of the editors have an option labelled ‘clean code’ or similar. Log into the backend /administrator/ section of your Joomla powered website and navigate to ‘mambots’ -> ‘site mambots’ -> click on your editor in the list. Over on the right hand side of the screen are the parameters. Turn off ‘clean code’ or whatever option your editor has. Save your settings and try again. Alternatively get a better editor that doesn’t second guess your wishes. On most client work we do the first thing we install is WysiwygPro.