When using the site from a browser with small screen size, the presentation of tables overflows the available space in screen.
Then tables have to be scrolled left and right to be able to use the content.

There are several issues with this:

• Reading blocks of texts is annoying: eg. issue descriptions, notes, etc. as the text is wider than screen, noot dynamically adapted to viewport width. You have to constantly scroll sideways to read the text
• Some tables may be acceptable (even preferable), due to the presentation of a lot of information, for example: view bugs list.
  but other seems not to be a requeriment. For example: forms like bug report page. View bug page would benefit for a dynamic layout too

i've set this to major severity, becasue i have the concept that the new UI was targeted to be responsive and adapted to a wide sort of devices.
In my opinion, as described, the current layout is not still at that stage.