I’m sure this came up before, and I thought I had even implemented the solution somewhere… but I’ve tried various searches and came up empty.
I want some elements in my wiki to be visible IFF the wiki is rendering within an iframe, but not when it’s being loaded directly (including, for example, a prominent invitation/link to open the site in its own tab or new window, plus hiding sidebar and other bulky elements, so the iframe can use limited space more efficiently).
I remember there are some variables that can be compared by javascript (variables such as window.location or window.top or window.name or window.self or window.parent …?) where the variables will match when we’re NOT being nested within an iframe…
And of course, we can also do this in a $:/tags/Stylesheet tiddler. But we will need the default type, text/vnd.tiddlywiki rather than text/css, since the latter does not handle wikitext markup.
Of course, I can replace low opacity with display:none; down the line, but at this point in developing my site, it’s nice to have faint visual confirmation — within my regular browser window — of the position of the conditional-display element.