Test Info:

```<!DOCTYPE html> ```
``` <html reftest-zoom="0.3"> ```
``` <head> ```
``` <!-- Default to invisible text --> ```
``` <style type="text/css" media="screen, print"> ```
``` .hidden { ```
``` color: white; ```
``` } ```
``` .visible { ```
``` color: black; ```
``` } ```
``` </style> ```
``` </head> ```
``` <body> ```
``` <!-- Nest successive radicals and test that the horizontal bar of one of them is drawn. ```
``` Because the comparison is for inequality with about:blank, at most one can be visible --> ```
``` <math> ```
``` <mrow> ```
``` <msqrt class="hidden"> ```
``` <mspace width="1em" height="1em" /> ```
``` <msqrt class="hidden"> ```
``` <mspace width="1em" height="1em" /> ```
``` <msqrt class="hidden"> ```
``` <mspace width="1em" height="1em" /> ```
``` <msqrt class="hidden"> ```
``` <mspace width="1em" height="1em" /> ```
``` <msqrt class="hidden"> ```
``` <mspace width="1em" height="1em" /> ```
``` <msqrt class="visible"> ```
``` <mspace width="1em" height="1em" /> ```
``` <msqrt class="hidden"> ```
``` <mspace width="20em" height="1em" /> ```
``` </msqrt> ```
``` </msqrt> ```
``` </msqrt> ```
``` </msqrt> ```
``` </msqrt> ```
``` </msqrt> ```
``` </msqrt> ```
``` </mrow> ```
``` </math> ```
``` ```
``` <!-- Block out all but the horizontal bar of the visible radical --> ```
``` <div style="position: absolute; top: 5px; left: 0px; ```
``` width: 20em; height: 10em; background: white;"></div> ```
``` </body> ```
```</html> ```