Updating notebook.less to use baseLineHeight from variables.

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

@@ -202,7 +202,7 div.prompt {
     font-family: monospace;
     text-align: right;
     /* This has to match that of the the CodeMirror class line-height below */	
-    line-height: 1.231;
+    line-height: @baseLineHeight;
 }
 
 div.input {
@@ -308,7 +308,7 div.output_text {
     color: @base_font_color;
     font-family: monospace;
     /* This has to match that of the the CodeMirror class line-height below */	
-    line-height: 1.231;
+    line-height: @baseLineHeight;
 }
 
 /* stdout/stderr are 'text' as well as 'stream', but pyout/pyerr are *not* streams */
@@ -368,7 +368,7 div.text_cell_render {
  */
 
 .CodeMirror {
-    line-height: 1.231;  /* Changed from 1em to our global default */
+    line-height: @baseLineHeight;  /* Changed from 1em to our global default */
 	height: auto;     /* Changed to auto to autogrow */
 	background: none;  /* Changed from white to allow our bg to show through */
 }