Navigation menu needs attention, reformats incorrectly

The top navigation menu needs a bit of work to deal with less than wide screens. If one shrinks the width of the browser's display the bottom line (for example, starting with admin's menu name) slips up and to the right when it ought stay against the left margin.
Also, shrinking a bit more to cause the triple bar icon to appear, clicking on it and its descendents keeps them present, with no obvious way of rolling them back up.
While doing shrinking note that the Drupal icon may appear at the upper left and then vanish upon further shrinkage.
Related to this no doubt is a further problem not tied to shrinkage per se. If one creates content pages with material at the top then the navigation menu usually covers it. A particular example of this is viewing Modules where the top text line shows through at the very top of the navigation area.
A common attribute of this behaviour is not firmly clamping sections to stay within their bounds, not drift up and to the right nor sneak up behind existing areas. Perhaps a few judicious <br>'s between <div>'s, or equivalent might help.