As I was getting problems with PHP cookies constantly disappearing (after about 15 - 30 minutes) I added some "header" lines immediately after "session_start":
session_start();
header("Cache-Control: no-cache");
header("Pragma: no-cache");
But now the page icons disappear when I click the back button. I am using Firefox 48, Apache/2.4.7 (Ubuntu) and PHP Version 5.5.9-1ubuntu4.19.
The HTML for the icon is just:
<link rel="icon" type="image/png" href="res/heart-icon.png">
Update
I found out why the cookies were disappearing (see Session variables disappearing). So I fixed that problem and then I just removed the two "header" lines above.
