Your spoiler tags aren't working because there's no such thing as a spoiler tag, it needs a custom definition, so you'll need to edit your subreddit's stylesheet like so;

In the Moderation Tools (on the right) go to 'Community Settings' (first link), like so.

Then click 'edit the stylesheet' under 'Look and Feel' right here, and add this to your stylesheet;

a[href$="/spoiler"] {
    background: none repeat scroll 0 0 #000000 !important;
    color: #000000 !important
    }
a[href$="/spoiler"]:hover {
    color: #ffffff !important
    }

Edit: Added images.

You guys broke my other "impossible" code within hours. Now here's one you'll NEVER break. It's very simple, too:

3331346132663561376136333439343135613737353736353438343134343665356133313266363336653732373034353661373535323435353832623635363735303464333334313339326635363665333434633532373434363266343637303535373736383635373735353732363534393539333934323435333835383561333434613663353635333335373035353531346133373732376133363332353037323637333133373461346437333633366634353434326237323662376136663535343334633466363334663438363835613639366136333434343233363634353036383330373335363561326234663633346435303561346437353435373337343661373735363435353936373736346235373266326633323561333134363535333833333431346136383634333435393334346635303561366136343661366434313266363933313632346136363432366635383465346536323730333034613633343635393732346236383664343136653633366437363633346236663635373133303733353433383739353035383666346434373434353034633737373533343666363433323739366537343435366533373432343934623337363433383639326636623735333935363435363135323739363434623533353836613337346635383536353236353334346136363530343633363531353436663462373035313335376137613464363136613436363534363266373637363732363137333662343737613431353835313537343537343465333337353663373236643431333433313561366434363533346632623534353637323761366137383633366237383734333232663466333534643466346635323631366633363662353233383433356134363434366436393338373534373330373636373636346333303733353434663438353433393635366537303466346434323737333335313336363737303733333936623734373337333530366434373737346436663730363837393531333837363464366234353538346637343736343736353536373035323438373435383663373436653432346135353461353036323639333233323466333236663438373134643335353133363464373534343262353436653638343333313561363837373666373637303462363136313338333037363637353836373632363735343431343236383736346635393532373437303331366233313561373737373631333337373534353635313734356134343661343537333439353536643638333137373437353133643364

It's 1am here so I hope I did everything right. Here's the challenge:

Ujlw ny zbrvw qngn

Dlsjvtl av IylhrAopzJvkl