But if you have downloaded a skin and now want to install it from hard disk offline?
There is one easiest way to build your own Firefox theme installer.
Copy the below code and paste it in notepad now save the file with .HTML extraction (example: Theme Installer.html)
And your Firefox theme installer is ready.
Open the HTML file with Firefox and browse the .JAR theme file from hard disk

<script type="text/javascript"> function installTheme(where) { var file = ''; if (where == 'local') { file = 'file:///' + escape(document.getElementById('filename').value.replace(/\\/g,'/')); } else { file = document.getElementById('url').value; } InstallTrigger.installChrome(InstallTrigger.SKIN, file, getName(file)); } function getName(raw) { var grabFileStart = raw.lastIndexOf('/'); var grabFileEnd = raw.lastIndexOf('.'); if (grabFileStart >= grabFileEnd) { return 'Invalid file name'; } else { return raw.substring(grabFileStart + 1,grabFileEnd); } } function installThemeNow(file) { InstallTrigger.installChrome(InstallTrigger.SKIN, file, getName(file)); return true; } </script> <style type="text/css"> <!-- .style2 { font-family: Verdana, Arial, Helvetica, sans-serif; font-weight: bold; font-size: 12px; } --> </style> <table width="80%" border="0" align="center" cellpadding="0" cellspacing="2" bgcolor="#0099FF"> <tr> <td bgcolor="#F5F4ED"><br><div align="center"><span class="style2">Install Firefox .JAR theme from Harddisk<br><br></span> <form><input id="filename" type="file"> <input value="Install" onclick="installTheme('local');" type="button"> </form> </div></td> </tr> </table>