CSS problem in IE

http://www.gula.org.il/wordpress/
This is a website that I built ion wordpress.

In both chrome and firefox you see it excellent.

However in IE the left border of the top left box is partially missing.

I have checked my css for validation and I found that except from vendor prefix I have no error.

So my question is what the cause for the problem and if you can suggest me a way to fix it.

The floated elements escape the overflow of their parents. There are several ways to bypass that problem. My favorite is to add an last empty div, in order to clear the floats:

Code:

---

<div class="parent">
        <div style="float:left">something</div>
        <div style="float:right">something</div>
        <div style="clear:both"></div>
</div>

---