Test Runs sections appears wrongly formatted in Test Executions if Zephyr is also enabled

When Zephyr for JIRA v4.0.1.40107450 is installed and enabled, the Test Runs section inside the Test Execution (This happens in the Test Runs section inside the Test too) appears wrongly formatted; it does not scroll to the right and the "Show xx entries" dropdown is not formatted correctly.

To reproduce: install Zephyr and enable it. 

Disabling Zephyr "fixes" the problem.

In the Test Execution, Test the Assignee and Reporter should have a normal font weight.
In the Test Run the Assignee should have a bold font weight.