fill #site height with notebook containers

avoids cutoff of overlay elements

IPython/html/static/notebook/less/notebook.less

@@ -8,12 +8,14 b''
 
 #ipython-main-app {
     .border-box-sizing();
+    height: 100%;
 }
 
 div#notebook_panel {
     margin: 0px;
     padding: 0px;
     .border-box-sizing();
+    height: 100%;
 }
 
 #notebook {
@@ -27,6 +29,7 b' div#notebook_panel {'
     margin: 0px;
     outline: none;
     .border-box-sizing();
+    min-height: 100%;
 }
 
 #notebook-container{

IPython/html/static/style/style.min.css

@@ -10358,6 +10358,7 b' h6:hover .anchor-link {'
   box-sizing: border-box;
   -moz-box-sizing: border-box;
   -webkit-box-sizing: border-box;
+  height: 100%;
 }
 div#notebook_panel {
   margin: 0px;
@@ -10365,6 +10366,7 b' div#notebook_panel {'
   box-sizing: border-box;
   -moz-box-sizing: border-box;
   -webkit-box-sizing: border-box;
+  height: 100%;
 }
 #notebook {
   font-size: 14px;
@@ -10379,6 +10381,7 b' div#notebook_panel {'
   box-sizing: border-box;
   -moz-box-sizing: border-box;
   -webkit-box-sizing: border-box;
+  min-height: 100%;
 }
 @media not print {
   #notebook-container {