How to Tag and Conceal Spoiler Text
[spoiler][/spoiler] tags work, and will blur individual words or a line -> like this. However, they do not wrap around multiple paragraphs.
To hide longer text with multiple paragraphs, highlight all the relevant text, and click the gear icon just above on your post. Select "Hide Details"
Text is hidden here using the Details tags!
This will wrap your text in
[details][/details] tags and fold it away until clicked.
You can change
[details="This text here"] to change what the header says.
For the fixed-width fonts, wrap your text in ` (shift tilde on most US keyboards)