diff --git a/layout/style/res/html.css b/layout/style/res/html.css
index 77962f643935c..803262aeb2887 100644
--- a/layout/style/res/html.css
+++ b/layout/style/res/html.css
@@ -873,14 +873,14 @@ rp {
 }
 rt {
   display: ruby-text;
+  font-size: 50%;
+  -moz-min-font-size-ratio: 50%;
 }
 rtc {
   display: ruby-text-container;
 }
 rtc, rt {
   white-space: nowrap;
-  font-size: 50%;
-  -moz-min-font-size-ratio: 50%;
   line-height: 1;
 %ifndef XP_WIN
   /* The widely-used Windows font Meiryo doesn't work fine with this
@@ -895,10 +895,6 @@ rtc, rt {
 rtc:lang(zh), rt:lang(zh) {
   ruby-align: center;
 }
-rtc:lang(zh-TW), rt:lang(zh-TW) {
-  font-size: 30%; /* bopomofo */
-  -moz-min-font-size-ratio: 30%;
-}
 rtc > rt {
   font-size: inherit;
 }