diff --git a/themes/classic/global/mac/splitter.css b/themes/classic/global/mac/splitter.css
index e37455d82ac4..c27c805a3388 100644
--- a/themes/classic/global/mac/splitter.css
+++ b/themes/classic/global/mac/splitter.css
@@ -18,6 +18,7 @@ grippy, grippy[collapse="before"]
     border-right          : 1px solid #9D9D9D;
     border-bottom         : 1px solid #9D9D9D;
 	padding               : 0px;
+  min-height            : 1px;
 	list-style-image      : url("chrome://global/skin/grippy-horizontal-before.gif");
 	cursor                : pointer;
   }
diff --git a/themes/classic/global/win/splitter.css b/themes/classic/global/win/splitter.css
index a3602fea0d99..f6d3d8e55f9e 100644
--- a/themes/classic/global/win/splitter.css
+++ b/themes/classic/global/win/splitter.css
@@ -20,6 +20,7 @@
       border                : 1px solid ThreeDShadow;
   	  list-style-image      : url("chrome://global/skin/grippy-horizontal-before.gif");
   	  cursor                : pointer;
+      min-height            : 1px;
     }
   
   grippy:hover
diff --git a/themes/classic/messenger/mac/messenger.css b/themes/classic/messenger/mac/messenger.css
index 7dac3e724991..d5fd1866f5a6 100644
--- a/themes/classic/messenger/mac/messenger.css
+++ b/themes/classic/messenger/mac/messenger.css
@@ -29,10 +29,6 @@
    display               : none;
   } 
 
-
-
-
-
 /**
  * toolbar button images
  */
@@ -452,6 +448,7 @@ splitter
  {
    border-bottom         : 1px solid #FFFFFF;
    border-left           : 1px solid #999999;
+   min-width             : 1px;
  }
 
 #threadOutliner > outlinerrows  > .outliner-bodybox
diff --git a/themes/classic/messenger/mac/msgHdrViewOverlay.css b/themes/classic/messenger/mac/msgHdrViewOverlay.css
index b0294f43b22d..3c8ad6510358 100644
--- a/themes/classic/messenger/mac/msgHdrViewOverlay.css
+++ b/themes/classic/messenger/mac/msgHdrViewOverlay.css
@@ -29,6 +29,12 @@ Rights Reserved.
 @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* set default namespace to HTML */
 @namespace html url("http://www.w3.org/1999/xhtml"); /* namespace for XUL elements */
 
+#collapsedHeaderView,
+#expandedHeaderView
+  {
+    min-width             : 1px;
+  }
+
 mail-emailaddress {
   -moz-binding: url(chrome://messenger/content/mailWidgets.xml#mail-emailaddress);
   display: -moz-xul-inline-box;
diff --git a/themes/classic/messenger/win/messenger.css b/themes/classic/messenger/win/messenger.css
index af89973adbe6..188699e6cf38 100644
--- a/themes/classic/messenger/win/messenger.css
+++ b/themes/classic/messenger/win/messenger.css
@@ -459,6 +459,7 @@ searchterm
   {
     border-bottom         : 1px solid ThreeDHighlight;
     border-left           : 1px solid ThreeDShadow;
+    min-width             : 1px;
   }
 
 #threadOutliner > .outliner-columns 
diff --git a/themes/classic/messenger/win/msgHdrViewOverlay.css b/themes/classic/messenger/win/msgHdrViewOverlay.css
index 25fe0f0df077..5d47043dad43 100644
--- a/themes/classic/messenger/win/msgHdrViewOverlay.css
+++ b/themes/classic/messenger/win/msgHdrViewOverlay.css
@@ -29,6 +29,12 @@
 @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* set default namespace to HTML */
 @namespace html url("http://www.w3.org/1999/xhtml"); /* namespace for XUL elements */
 
+#collapsedHeaderView,
+#expandedHeaderView
+  {
+    min-width             : 1px;
+  }
+
 mail-emailaddress 
   {
     -moz-binding          : url(chrome://messenger/content/mailWidgets.xml#mail-emailaddress);
diff --git a/themes/modern/messenger/messenger.css b/themes/modern/messenger/messenger.css
index 1a137d133072..19a44c2bba4e 100644
--- a/themes/modern/messenger/messenger.css
+++ b/themes/modern/messenger/messenger.css
@@ -463,6 +463,7 @@ searchterm {
   border-right: none;
   border-bottom: 1px solid #C6D3D6;
   border-left: 1px solid #63717B;
+  min-width: 1px;
 }
 
 #threadOutliner > outlinerrows {
diff --git a/themes/modern/messenger/msgHdrViewOverlay.css b/themes/modern/messenger/msgHdrViewOverlay.css
index a77c4b88a094..b6876f9ce24b 100644
--- a/themes/modern/messenger/msgHdrViewOverlay.css
+++ b/themes/modern/messenger/msgHdrViewOverlay.css
@@ -30,6 +30,11 @@
 
 /* ::::: msg header toolbars ::::: */
 
+#collapsedHeaderView,
+#expandedHeaderView {
+  min-width: 1px;
+}
+
 #msgHeaderView {
   border-bottom: 1px solid #000000;
 }