The Kunena team has announce the arrival of Kunena 7.0.4 [K 7.0.4] in stable which is now available for download as a native Joomla extension for J! 5.4.x/6.0.x. This version addresses most of the issues that were discovered in K 6.2 / K 6.3 / K 6.4 and issues discovered during the last development stages of K 7.0
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If you used Firebug for Firefox you would have found (within one minute) that all you need to do is modify the CSS file by adding the line (in red) below:
As you like - it's your website. It's really better to hide these things than to edit the source code. Editing the source code may save you a millisecond or two but could cost you hours, later, when you need to upgrade to new versions because of other issues. K 1.6.1 is just around the corner (which contains dozens of fixes to K 1.6.0) and you're only going to have to do those changes again. Then there will probably be a K 1.6.2 (and so on) and, again, you're going to have to make those changes. But, like I said, it's your website.