diff --git a/src/main/gtk-3.0/gtk-dark-blue.css b/src/main/gtk-3.0/gtk-dark-blue.css
index 9068d9d4..ad50bad4 100644
--- a/src/main/gtk-3.0/gtk-dark-blue.css
+++ b/src/main/gtk-3.0/gtk-dark-blue.css
@@ -7255,7 +7255,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #242424;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-dark-green.css b/src/main/gtk-3.0/gtk-dark-green.css
index 468f6545..0ba83279 100644
--- a/src/main/gtk-3.0/gtk-dark-green.css
+++ b/src/main/gtk-3.0/gtk-dark-green.css
@@ -7255,7 +7255,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #242424;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-dark-grey.css b/src/main/gtk-3.0/gtk-dark-grey.css
index 2c969a55..7611f99c 100644
--- a/src/main/gtk-3.0/gtk-dark-grey.css
+++ b/src/main/gtk-3.0/gtk-dark-grey.css
@@ -7255,7 +7255,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #242424;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-dark-orange.css b/src/main/gtk-3.0/gtk-dark-orange.css
index ccce8e34..3e2583df 100644
--- a/src/main/gtk-3.0/gtk-dark-orange.css
+++ b/src/main/gtk-3.0/gtk-dark-orange.css
@@ -7255,7 +7255,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #242424;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-dark-pink.css b/src/main/gtk-3.0/gtk-dark-pink.css
index de41e1c8..1ce38610 100644
--- a/src/main/gtk-3.0/gtk-dark-pink.css
+++ b/src/main/gtk-3.0/gtk-dark-pink.css
@@ -7255,7 +7255,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #242424;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-dark-purple.css b/src/main/gtk-3.0/gtk-dark-purple.css
index f0107703..2db37093 100644
--- a/src/main/gtk-3.0/gtk-dark-purple.css
+++ b/src/main/gtk-3.0/gtk-dark-purple.css
@@ -7255,7 +7255,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #242424;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-dark-red.css b/src/main/gtk-3.0/gtk-dark-red.css
index 6a17b486..f43545fe 100644
--- a/src/main/gtk-3.0/gtk-dark-red.css
+++ b/src/main/gtk-3.0/gtk-dark-red.css
@@ -7255,7 +7255,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #242424;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-dark-solid-blue.css b/src/main/gtk-3.0/gtk-dark-solid-blue.css
index 310d4274..ebb1bab0 100644
--- a/src/main/gtk-3.0/gtk-dark-solid-blue.css
+++ b/src/main/gtk-3.0/gtk-dark-solid-blue.css
@@ -7259,7 +7259,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #242424;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-dark-solid-green.css b/src/main/gtk-3.0/gtk-dark-solid-green.css
index 0d867fa1..3bff9906 100644
--- a/src/main/gtk-3.0/gtk-dark-solid-green.css
+++ b/src/main/gtk-3.0/gtk-dark-solid-green.css
@@ -7259,7 +7259,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #242424;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-dark-solid-grey.css b/src/main/gtk-3.0/gtk-dark-solid-grey.css
index 404f7151..d632c6ad 100644
--- a/src/main/gtk-3.0/gtk-dark-solid-grey.css
+++ b/src/main/gtk-3.0/gtk-dark-solid-grey.css
@@ -7259,7 +7259,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #242424;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-dark-solid-orange.css b/src/main/gtk-3.0/gtk-dark-solid-orange.css
index 1a0153ca..144b7bc0 100644
--- a/src/main/gtk-3.0/gtk-dark-solid-orange.css
+++ b/src/main/gtk-3.0/gtk-dark-solid-orange.css
@@ -7259,7 +7259,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #242424;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-dark-solid-pink.css b/src/main/gtk-3.0/gtk-dark-solid-pink.css
index f8871433..a98debd4 100644
--- a/src/main/gtk-3.0/gtk-dark-solid-pink.css
+++ b/src/main/gtk-3.0/gtk-dark-solid-pink.css
@@ -7259,7 +7259,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #242424;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-dark-solid-purple.css b/src/main/gtk-3.0/gtk-dark-solid-purple.css
index d73f7566..3a16f15c 100644
--- a/src/main/gtk-3.0/gtk-dark-solid-purple.css
+++ b/src/main/gtk-3.0/gtk-dark-solid-purple.css
@@ -7259,7 +7259,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #242424;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-dark-solid-red.css b/src/main/gtk-3.0/gtk-dark-solid-red.css
index 75e1d46c..c2111e84 100644
--- a/src/main/gtk-3.0/gtk-dark-solid-red.css
+++ b/src/main/gtk-3.0/gtk-dark-solid-red.css
@@ -7259,7 +7259,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #242424;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-dark-solid-yellow.css b/src/main/gtk-3.0/gtk-dark-solid-yellow.css
index 76949065..5a4ff54e 100644
--- a/src/main/gtk-3.0/gtk-dark-solid-yellow.css
+++ b/src/main/gtk-3.0/gtk-dark-solid-yellow.css
@@ -7259,7 +7259,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #242424;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-dark-solid.css b/src/main/gtk-3.0/gtk-dark-solid.css
index 3eee88c2..9325d065 100644
--- a/src/main/gtk-3.0/gtk-dark-solid.css
+++ b/src/main/gtk-3.0/gtk-dark-solid.css
@@ -7259,7 +7259,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #242424;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-dark-yellow.css b/src/main/gtk-3.0/gtk-dark-yellow.css
index 0fa8a7f6..adef04f7 100644
--- a/src/main/gtk-3.0/gtk-dark-yellow.css
+++ b/src/main/gtk-3.0/gtk-dark-yellow.css
@@ -7255,7 +7255,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #242424;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-dark.css b/src/main/gtk-3.0/gtk-dark.css
index cad4dbf3..ef388120 100644
--- a/src/main/gtk-3.0/gtk-dark.css
+++ b/src/main/gtk-3.0/gtk-dark.css
@@ -7255,7 +7255,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #242424;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-light-blue.css b/src/main/gtk-3.0/gtk-light-blue.css
index 4584fd96..48321af4 100644
--- a/src/main/gtk-3.0/gtk-light-blue.css
+++ b/src/main/gtk-3.0/gtk-light-blue.css
@@ -7271,7 +7271,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #ffffff;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-light-green.css b/src/main/gtk-3.0/gtk-light-green.css
index 65517fd9..f7ca4e21 100644
--- a/src/main/gtk-3.0/gtk-light-green.css
+++ b/src/main/gtk-3.0/gtk-light-green.css
@@ -7271,7 +7271,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #ffffff;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-light-grey.css b/src/main/gtk-3.0/gtk-light-grey.css
index d7a295e6..ed26ff28 100644
--- a/src/main/gtk-3.0/gtk-light-grey.css
+++ b/src/main/gtk-3.0/gtk-light-grey.css
@@ -7271,7 +7271,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #ffffff;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-light-orange.css b/src/main/gtk-3.0/gtk-light-orange.css
index 6891d204..cad83352 100644
--- a/src/main/gtk-3.0/gtk-light-orange.css
+++ b/src/main/gtk-3.0/gtk-light-orange.css
@@ -7271,7 +7271,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #ffffff;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-light-pink.css b/src/main/gtk-3.0/gtk-light-pink.css
index 3ee1c962..7794d7c4 100644
--- a/src/main/gtk-3.0/gtk-light-pink.css
+++ b/src/main/gtk-3.0/gtk-light-pink.css
@@ -7271,7 +7271,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #ffffff;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-light-purple.css b/src/main/gtk-3.0/gtk-light-purple.css
index ed9f0eaa..36449698 100644
--- a/src/main/gtk-3.0/gtk-light-purple.css
+++ b/src/main/gtk-3.0/gtk-light-purple.css
@@ -7271,7 +7271,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #ffffff;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-light-red.css b/src/main/gtk-3.0/gtk-light-red.css
index f7d096e7..5674a0d9 100644
--- a/src/main/gtk-3.0/gtk-light-red.css
+++ b/src/main/gtk-3.0/gtk-light-red.css
@@ -7271,7 +7271,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #ffffff;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-light-solid-blue.css b/src/main/gtk-3.0/gtk-light-solid-blue.css
index bc5fee78..bc061505 100644
--- a/src/main/gtk-3.0/gtk-light-solid-blue.css
+++ b/src/main/gtk-3.0/gtk-light-solid-blue.css
@@ -7275,7 +7275,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #ffffff;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-light-solid-green.css b/src/main/gtk-3.0/gtk-light-solid-green.css
index b98e331f..17ef0b05 100644
--- a/src/main/gtk-3.0/gtk-light-solid-green.css
+++ b/src/main/gtk-3.0/gtk-light-solid-green.css
@@ -7275,7 +7275,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #ffffff;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-light-solid-grey.css b/src/main/gtk-3.0/gtk-light-solid-grey.css
index a335b0e8..a168cb59 100644
--- a/src/main/gtk-3.0/gtk-light-solid-grey.css
+++ b/src/main/gtk-3.0/gtk-light-solid-grey.css
@@ -7275,7 +7275,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #ffffff;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-light-solid-orange.css b/src/main/gtk-3.0/gtk-light-solid-orange.css
index a913440e..74288533 100644
--- a/src/main/gtk-3.0/gtk-light-solid-orange.css
+++ b/src/main/gtk-3.0/gtk-light-solid-orange.css
@@ -7275,7 +7275,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #ffffff;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-light-solid-pink.css b/src/main/gtk-3.0/gtk-light-solid-pink.css
index c20a422d..4bbe6584 100644
--- a/src/main/gtk-3.0/gtk-light-solid-pink.css
+++ b/src/main/gtk-3.0/gtk-light-solid-pink.css
@@ -7275,7 +7275,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #ffffff;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-light-solid-purple.css b/src/main/gtk-3.0/gtk-light-solid-purple.css
index be1f5df8..e333a716 100644
--- a/src/main/gtk-3.0/gtk-light-solid-purple.css
+++ b/src/main/gtk-3.0/gtk-light-solid-purple.css
@@ -7275,7 +7275,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #ffffff;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-light-solid-red.css b/src/main/gtk-3.0/gtk-light-solid-red.css
index f637ad9e..31993345 100644
--- a/src/main/gtk-3.0/gtk-light-solid-red.css
+++ b/src/main/gtk-3.0/gtk-light-solid-red.css
@@ -7275,7 +7275,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #ffffff;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-light-solid-yellow.css b/src/main/gtk-3.0/gtk-light-solid-yellow.css
index fdd36e69..47aa4f34 100644
--- a/src/main/gtk-3.0/gtk-light-solid-yellow.css
+++ b/src/main/gtk-3.0/gtk-light-solid-yellow.css
@@ -7275,7 +7275,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #ffffff;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-light-solid.css b/src/main/gtk-3.0/gtk-light-solid.css
index f92cfe32..23cba89c 100644
--- a/src/main/gtk-3.0/gtk-light-solid.css
+++ b/src/main/gtk-3.0/gtk-light-solid.css
@@ -7275,7 +7275,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #ffffff;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-light-yellow.css b/src/main/gtk-3.0/gtk-light-yellow.css
index 2dae4d2c..e07567e7 100644
--- a/src/main/gtk-3.0/gtk-light-yellow.css
+++ b/src/main/gtk-3.0/gtk-light-yellow.css
@@ -7271,7 +7271,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #ffffff;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/main/gtk-3.0/gtk-light.css b/src/main/gtk-3.0/gtk-light.css
index b928cbc6..84a0d308 100644
--- a/src/main/gtk-3.0/gtk-light.css
+++ b/src/main/gtk-3.0/gtk-light.css
@@ -7271,7 +7271,8 @@ window#GearyMainWindow.background.csd > overlay > box.vertical > paned > .sideba
 
 .geary-main-window.background.csd stack#conversation_viewer,
 window#GearyMainWindow.background.csd stack#conversation_viewer {
-  border-bottom-right-radius: 12px;
+  background-color: #ffffff;
+  border-bottom-right-radius: 13px;
 }
 
 .geary-main-window.background.csd stack#conversation_viewer scrolledwindow.geary-conversation-scroller viewport.frame,
diff --git a/src/sass/gtk/_applications.scss b/src/sass/gtk/_applications.scss
index e489fcc8..253a990d 100644
--- a/src/sass/gtk/_applications.scss
+++ b/src/sass/gtk/_applications.scss
@@ -2773,10 +2773,7 @@ window#whiskermenu-window {
   }
 }
 
-//
-//  * Thunar *
-//
-
+// Thunar
 window.background.csd.thunar {
   > grid.horizontal > paned.horizontal > scrolledwindow.frame.sidebar.shortcuts-pane {
     border-bottom-left-radius: $wm_radius;
@@ -2894,7 +2891,8 @@ window#GearyMainWindow.background.csd {
   }
 
   stack#conversation_viewer {
-    border-bottom-right-radius: $wm_radius;
+    background-color: $base_color;
+    border-bottom-right-radius: $wm_radius + 1px;
 
     scrolledwindow.geary-conversation-scroller {
       viewport.frame {