Fine tuning of notebook styles.

* Padding added to L/R of notebook div (40px).
* Margin added to T/B of cells (15px).
* Margin added to T of output div (15px).
* More elements using border-box layout mode.

IPython/frontend/html/notebook/static/css/notebook.css

@@ -136,7 +136,7 b' div.notebook {'
     height: 15px;
     overflow-y: auto;
     overflow-x: hidden;
-    padding: 5px;
+    padding: 0px 40px;
     background-color: white;
     font-size: 12pt;
 
@@ -153,6 +153,8 b' div.notebook {'
 div.cell {
     width: 100%;
     padding: 5px;
+    /* This acts as a spacer between cells, that is outside the border */
+    margin: 15px 0px 15px 0px;
     position: relative;
 
     box-sizing: border-box;
@@ -166,6 +168,9 b' div.cell {'
     box-orient: vertical;
     -webkit-box-orient: vertical;
     -moz-box-orient: vertical;
+
+/*    border-width: 1px;*/
+/*    border-style: solid;*/
 }
 
 div.code_cell {
@@ -187,6 +192,13 b' div.input {'
     box-orient: horizontal;
     -webkit-box-orient: horizontal;
     -moz-box-orient: horizontal;
+
+    box-sizing: border-box;
+    -moz-box-sizing: border-box;
+    -webkit-box-sizing: border-box;
+
+/*    border-width: 1px;*/
+/*    border-style: solid;*/
 }
 
 div.input_prompt {
@@ -217,6 +229,9 b' textarea.input_textarea {'
 }
 
 div.output {
+    /* This is a spacer between the input and output of each cell */
+    margin-top: 15px;
+
     display: box;
     display: -webkit-box;
     display: -moz-box;
@@ -224,6 +239,13 b' div.output {'
     box-orient: vertical;
     -webkit-box-orient: vertical;
     -moz-box-orient: vertical;
+
+    box-sizing: border-box;
+    -moz-box-sizing: border-box;
+    -webkit-box-sizing: border-box;
+
+/*    border-width: 1px;*/
+/*    border-style: solid;*/
 }
 
 div.output_pyout {