People have been increasingly having issues with Mibbit as a web client when trying to access IRC. Between the ads, disconnects, and virus warnings I had to give it up months ago. I've since found a much more stable, ad-free web client :) The first time you log in, it's a bit tricky as you have to click a small blue link in order to put in the irc address. But otherwise it's pretty simple. Once you log in, there's a gear icon in the upper right corner where you can change some of your interface settings to suit you better. I've put pics below that should show the basics of logging in.
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