The 2 column styling was updated for 1.2.3, so it is possible something changed. Will look into it asap.

Well, this one is HARD!

Turns out there was a serious bug for mobile display in the 2 and 3 column blog layouts – and they use .content-2-col and .content-3-col. In your example, I can’t quite figure out why it is broken, but I don’t think I can go back to how it was. The “fix” involved how clear is being handled.

So – content-2/3-col are really intended for the blog column settings, and it has just been good fortune so far that they worked for general usage. They don’t any more, and I don’t think I can fix this.

There is a very easy fix – change your usage of content-2-col to content-2-col-left and content-2-col-right. There may be issues with 3 cols that will have to be addressed.

@weaver, it looks to me like the problem comes from an error in the nth of type rule you are using

You have

:nth-of-type(2n).content-2-col, :nth-of-type(3n+1).content-3-col {clear:left;}

But I think it should be

:nth-of-type(2n+1).content-2-col, :nth-of-type(3n+1).content-3-col {clear:left;}

You also have the same problem with

.is-mobile .content-3-col:nth-of-type(2n){clear:left!important}

that should be

.is-mobile .content-3-col:nth-of-type(2n+1){clear:left!important}

But you are also missing the removal of the clear set in the desktop rule.

It should actually be

.is-mobile :nth-of-type(3n+1).content-3-col {clear:none;}
.is-mobile .content-3-col:nth-of-type(2n+1){clear:left!important}

There will be a fix for this later this afternoon.

There will also be an update for the Weaver Xtreme Theme Support plugin at the same time. Update the Theme Support plugin, and the new version of Weaver Xtreme will be included on the WP Dashboard Updates admin panel.

If you are using .content-3-col directly (instead of just for blogs), you may need to wrap your <div class=”content-3-col”></div>s inside a blank <div> </div>. This is due to the way the CSS now works for these layouts.

We worked really hard yesterday to get this to work right – the main goal was to get the blog 2 and 3 column layout to work properly.

Previous versions of Weaver Xtreme had used an entirely different method to get the columns to work, but it turned out that that method did not always work on mobile devices as expected. The problem turns out to have been lurking for a long time, but no one really figured it out until very recently.

So the new method is to use a CSS3 property called :nth-of-type. The way CSS counts these requires that they be inside a <div> for the counting to work reliably. So in order to use these classes (.content-2-col and .content-3-col) manually, you have to wrap them all in a <div> </div>. There seems to be no nice way around this issue.

And this also means that multiple columns will work on IE8, but may sometime have “funny” breaking points depending on the height of each column. The days of totally perfect support for IE8 are past. It is no longer worth crippling sites on modern browsers simply to keep IE8 total compatibility. Weaver Xtreme sites look very good on IE8, but will not always be “perfect”, but will degrade gracefully.