diff --git a/themes/bootstrap/scss/_common.scss b/themes/bootstrap/scss/_common.scss
index 3dbf5bccdc..0f95ae2eff 100644
--- a/themes/bootstrap/scss/_common.scss
+++ b/themes/bootstrap/scss/_common.scss
@@ -345,7 +345,7 @@ fieldset {
     -webkit-box-shadow: 3px 3px 15px #bbb;
     box-shadow: 3px 3px 15px #bbb;
     width: initial;
-    font-size: 1rem;
+    font-size: 1em;
   }
 }
 
diff --git a/themes/metro/scss/_common.scss b/themes/metro/scss/_common.scss
index 2d59a5a555..ee2a027c28 100644
--- a/themes/metro/scss/_common.scss
+++ b/themes/metro/scss/_common.scss
@@ -363,7 +363,7 @@ fieldset {
 legend {
   padding: 0 5px;
   width: initial;
-  font-size: 1rem;
+  font-size: 1em;
 }
 
 .some-margin {
diff --git a/themes/original/scss/_common.scss b/themes/original/scss/_common.scss
index 8e9ba5ebf7..31ac3493a9 100644
--- a/themes/original/scss/_common.scss
+++ b/themes/original/scss/_common.scss
@@ -119,7 +119,7 @@ fieldset {
     color: #444;
     background-color: transparent;
     width: initial;
-    font-size: 1rem;
+    font-size: 1em;
   }
 }