diff --git a/stylesheets/_conversation.scss b/stylesheets/_conversation.scss
index 5c4531a423f1..6143abc3c514 100644
--- a/stylesheets/_conversation.scss
+++ b/stylesheets/_conversation.scss
@@ -45,6 +45,9 @@
 }
 
 .message-detail {
+  .container {
+    height: calc(100% - (#{$header-height} + 4px));
+  }
 
   .message-container {
     background: white;
diff --git a/stylesheets/manifest.css b/stylesheets/manifest.css
index a0642f8e113c..eb3c812b1b0a 100644
--- a/stylesheets/manifest.css
+++ b/stylesheets/manifest.css
@@ -571,6 +571,8 @@ input.search {
     font-family: monospace;
     padding: 0 1em; }
 
+.message-detail .container {
+  height: calc(100% - (36px + 4px)); }
 .message-detail .message-container {
   background: white;
   padding: 1em 0; }