overriding baseLineHeight is not a good idea

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

@@ -2,9 +2,9 b''
 
 @textColor:             @black;
 @baseFontSize:          13px;
-@baseLineHeight:        1.231;
-@monoFontFamily:		monospace;  // to allow user to customize their fonts
+@monoFontFamily:        monospace;  // to allow user to customize their fonts
 
 // Our own global variables for all pages go here
 
-@corner_radius:					4px;
  No newline at end of file
+@corner_radius:         4px;
+@code_line_height:      1.231em;

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

@@ -10,7 +10,7 b''
  */
 
 .CodeMirror {
-    line-height: @baseLineHeight;  /* Changed from 1em to our global default */
+    line-height: @code_line_height;  /* 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 */
 }

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

@@ -37,7 +37,7 b' div.output_text {'
     color: @textColor;
     font-family: @monoFontFamily;
     /* This has to match that of the the CodeMirror class line-height below */	
-    line-height: @baseLineHeight;
+    line-height: @code_line_height;
 }
 
 /* stdout/stderr are 'text' as well as 'stream', but pyout/pyerr are *not* streams */

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

@@ -13,7 +13,7 b' div#pager {'
 	
 	pre {
 		font-size:			@baseFontSize;
-		line-height: 		@baseLineHeight;
+		line-height: 		@code_line_height;
 		color: 				@textColor;
 		background-color: 	@cell_background;
 		padding:			0.4em;