Fix the Y positioning of the handle

- The additional translateY makes djdt.top=0 move the handle to the top
  of the browser window.
- Because the handle is rotated we have to subtract its offsetWidth, not
  its offsetHeight to keep it in bounds at the bottom of the window.

Author: matthiask

debug_toolbar/static/debug_toolbar/css/toolbar.css

@@ -198,7 +198,7 @@
 
 #djDebug #djDebugToolbarHandle {
     position: fixed;
-    transform: rotate(-90deg);
+    transform: translateY(-100%) rotate(-90deg);
     transform-origin: right bottom;
     background-color: #fff;
     border: 1px solid #111;

debug_toolbar/static/debug_toolbar/js/toolbar.js

@@ -222,7 +222,7 @@ const djdt = {
         if (handleTop) {
             handleTop = Math.min(
                 handleTop,
-                window.innerHeight - handle.offsetHeight
+                window.innerHeight - handle.offsetWidth
             );
             handle.style.top = handleTop + "px";
         }