Copyleft symbol
At this time there is no copyleft symbol in the Unicode character encoding standard. Some methods consist in using the copyright symbol and apply a symmetry on it. Here is how.
HTML:
<p><span class="copyleft">©</span> Copyleft ...</p>
CSS:
.copyleft {
display: inline-block;
-moz-transform: scaleX(-1);
-o-transform: scaleX(-1);
-webkit-transform: scaleX(-1);
transform: scaleX(-1);
filter: FlipH;
-ms-filter: "FlipH";
}
Note that I prefer writing Copyleft next to the symbol, because it is still semantically considered as a copyright one. Also, a lot of old browsers may not display it correctly.