Settings: Desaturate the navbar a bit.

chrome/browser/resources/shared/css/chrome_shared.css

 /* Styles common to WebUI pages that share the options pages style */
 body {
   cursor: default;
   font-size: 13px;
 }
 
 a:link {
   color: rgb(63, 110, 194);
 }
 
 a:active {
   color: rgb(37, 64, 113);
 }
 
 #navbar-content-title {
   -webkit-padding-end: 24px;
   -webkit-user-select: none;
-  color: #53637d;
+  color: #333;
   cursor: pointer;
   font-size: 200%;
   font-weight: normal;
   margin: 0;
   padding-bottom: 14px;
   padding-top: 13px;
   text-align: end;
   text-shadow: white 0 1px 2px;
 }
 
 #main-content {
   display: -webkit-box;
   position: absolute;
   left: 0;
   right: 0;
   top: 0;
   bottom: 0;
 }
 
 #navbar {
   margin: 0;
 }
 
 #navbar-container {
   -webkit-border-end: 1px solid #c6c9ce;
-  background: -webkit-linear-gradient(rgba(234, 238, 243, 0.2), #eaeef3),
-              -webkit-linear-gradient(left, #eaeef3, #eaeef3 97%, #d3d7db);
+  background-color: #f1f1f1;
   position: fixed;
   bottom: 0;
   /* We set both left and right for the sake of RTL. */
   left: 0;
   right: 0;
   top: 0;
   width: 216px;
   z-index: 2;
 }
 
-html[dir='rtl'] #navbar-container {
-  background: -webkit-linear-gradient(rgba(234, 238, 243, 0), #EAEEF3),
-              -webkit-linear-gradient(right, #EAEEF3, #EAEEF3 97%, #D3D7DB);
-}
-
 html.hide-menu #navbar-container {
   display: none;
 }
 
 #navbar-container > ul {
   -webkit-user-select: none;
   list-style-type: none;
   margin: 0;
   padding: 0;
 }
 
 .navbar-item {
   border-bottom: 1px solid transparent;
   border-top: 1px solid transparent;
-  color: #426dc9;
+  color: #333;
   cursor: pointer;
   display: block;
   font-size: 105%;
   outline: none;
   padding: 7px 0;
   text-align: end;
   text-shadow: white 0 1px 1px;
   -webkit-padding-end: 24px;
 }
 
 .navbar-item:focus {
   border-bottom: 1px solid #8faad9;
   border-top: 1px solid #8faad9;
 }
 
 .navbar-item-selected {
   -webkit-box-shadow: 0px 1px 0px #f7f7f7;
-  background: -webkit-linear-gradient(left, #bbcee9, #bbcee9 97%, #aabedc);
+  background-color: #bbcee9;
   border-bottom: 1px solid #8faad9;
   border-top: 1px solid #8faad9;
   color: black;
   text-shadow: #bbcee9 0 1px 1px;
 }
 
 #mainview {
   -webkit-box-align: stretch;
   -webkit-padding-start: 216px;
   margin: 0;
@@ skipping 93 matching lines @@
  */
 html[dir='rtl'] input.weakrtl::-webkit-input-placeholder,
 html[dir='rtl'] .weakrtl input::-webkit-input-placeholder {
   direction: rtl;
 }
 
 .page h1 {
   -webkit-padding-end: 24px;
   -webkit-user-select: none;
   border-bottom: 1px solid #eeeeee;
-  color: #53637d;
+  color: #333;
   font-size: 200%;
   font-weight: normal;
   margin: 0;
   padding-bottom: 4px;
   padding-top: 13px;
   text-shadow: white 0 1px 2px;
 }