A display bug at www.codeigniter.com

I am unable to reproduce this problem. The site adapts to changing browser window sizes nicely for me, using Firefox 31 on CentOS6.
Which browser and O/S platform are you using?

I use Windows 8.1 pro x64 and Firefox 34.0.5.
This bug also occurs in Chrome 31.0.1650.63. And,some webkit-based browser in Windows 7 and Windows server 2008 R2 have the same problem.
And on my thinkpad 8(a touch-screen Windows 8.1 device), Firefox can also see that.
But it works fine in Chrome 39.0.2171.71(and new version of Chrome seems to have better font render methods).
Internet Explorer 11, no issues.

I have found the problem. It's likely to be caused by Arial Bold (Windows 8.1 doesn't have built-in Helvetica and Ubuntu font) and the way that font displays.

The problem is--In Firefox and some other browser, when the font size is 16px, Arial bold's actual height is 1px more than Arial.This makes the first block (Download) 1px longer than the other blocks, and causes this problem.
(but 14px Arial is OK, confusing...)
Like this:
[attachment=32]
[attachment=33]
And this is the same page in the latest stable version of Google Chrome.
[attachment=31]

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