Edit: Anything depending on unicode characters depends on a) what characters exist in the fonts available to the client and b) what characters and unicode features are supported by the browser. Both are generally pretty bad.
This is an example of something that works in Webkit browsers (Chrome, Safari... but not Firefox which mangles these characters) on a machine that has access to fonts that support a sufficiently wide range of glyphs (e.g. a Mac which comes with the Apple Symbols fonts).
Naturally it's only suitable if you can predict or control the machines your users are using. This might be okay if it's for a bug control system used by a small team. Definitely not for public consumption.
The benefit for this pretty hefty cost is, it's a way to get symbols into publishing systems like the ones described in the question where you can't add images, custom code, HTML markup, etc, only text characters.
⃔ (Combining anti-clockwise arrow above 0x20D4) is a diacritic mark in the group Combining Diacritical Marks for Symbols, meaning it appears over the previous character, like so⃔...⃔.. Or there's ⃕ which is the same thing going the other way...⃕..
You can therefore create a kind of sync symbol using nothing but unicode characters by using it after a suitable character going the other way.
Examples (note they're all live text you can copy and paste):
- ⤻⃔ where ⃔ follows ⤻ Bottom arc anticlockwise arrow 0x293b is the obvious combination, but in the font and styling used on this site, they're too close together to be clear. You might be able to style it to look better.
- ⤿⃔ where ⃔ follow ⤿ from the block Supplemental Arrows-B looks better in this font and style.
- ⤾⃕ is the opposite of the above with ⃕ following ⤾ and doesn't seem to work so well.
- ⤻⃛⃔ is an example of the sort of thing you can do by stacking multiple diacritics. This includes another of the 'Combining...for symbols' set. Since it's a diacritic that appears above its combining character, and it's between two arrows, it increases the gap, making the symbol clearer. It's the first I found that combined with the arrow and increased the height, you might find something better.
↵⃗⃞ is an example using the square style, and can be made using ↵ followed by the diacritics ⃗ and, optionally, ⃞ if you want it in a box.
This gives you something resembling a sync symbol that works in common fonts like Arial, Verdana etc, using nothing but unicode characters (no additional HTML or CSS required).
Quick explanation of combining diacritics for anyone baffled: They're characters that modify the character before them. Diacritics are used a lot in European languages: for example one way to get an 'a' with an accent (
á) can be made by typing
Once entered on a computer, they combine with whatever went before them and are from there on treated as one character (and where a glyph already exists for that character combination, they're replaces with that glyph, a bit like a ligature). It would be annoying to need to hit delete twice to delete
So, to make them, you have to enter a 'pure' diacritic after the character you combine it with. You can do this by copying from the 'pure' samples on sites I link to (though occasionally people maintaining those sites accidentally make mistakes and post 'used' diacritics), or, do whatever the normal method is for entering special characters on your operating system.
It won't work if you just copy the examples, as they're already combined with something (even if it's just a space).