Make tips and their links readable in all themes....

chrome/browser/resources/new_tab_theme.css

 html {
   background-image:url(chrome://theme/theme_ntp_background?$1);
   background-color:$2;
   background-position:$3;
   background-repeat:$5;
   overflow:hidden;
 }
 html[bookmarkbarattached='true'] {
   background-position:$4;
 }
@@ skipping 37 matching lines @@
   background-color: $7;
   color: white;
 }
 
 #recently-closed {
   border-color: $$2; /* color_section_border */
   background-color: $$1; /* COLOR_NTP_SECTION */
   color: $$3; /* COLOR_NTP_SECTION_TEXT */
 }
 #recently-closed span,
-#recently-closed a,
-#recently-closed a:link,
-#tip-line a {
+#recently-closed a {
   color: $$4; /* COLOR_NTP_SECTION_LINK */
   text-decoration:underline;
 }
 
 #attribution {
   display : $$5;
   color: $9;
   text-align:right;
 }
 
 #tip-line {
-  color: $$8;
+  color: $8; /* COLOR_NTP_TEXT */
 }
+
+#tip-line a {
+  color: $9; /* COLOR_NTP_LINK */
+  text-decoration: underline;
+}