Use more yellowish color for ansiyellow

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

@@ -1,13 +1,12 @@
 /* CSS font colors for translated ANSI colors. */
 
-
 .ansibold {font-weight: bold;}
 
 /* use dark versions for foreground, to improve visibility */
 .ansiblack {color: black;}
 .ansired {color: darkred;}
 .ansigreen {color: darkgreen;}
-.ansiyellow {color: brown;}
+.ansiyellow {color: #c4a000;}
 .ansiblue {color: darkblue;}
 .ansipurple {color: darkviolet;}
 .ansicyan {color: steelblue;}
@@ -22,4 +21,3 @@
 .ansibgpurple {background-color: magenta;}
 .ansibgcyan {background-color: cyan;}
 .ansibggray {background-color: gray;}
-