I just wanted to point out that, in case you wanted to make spoiler text COMPLETELY invisible, you can do it by using the following mechanism for the spoiler tag:
<B><I>(SPOILER)</I></B> <font color=00243A style="background-color:00243A;">{param}</font>
<B><I>(SPOILER)</I></B> <font color=#00243A style=background-color:#00243A;>{param}</font>
If you want to alter the tag, feel free to do so. If not, just ignore me.
Peace
Aaron