themes: Fix incorrect blur and opacity interaction

Chrome sometimes seems to have problems when using a blur
backdrop-filter in combination with opacity. On Linux, this often
results in the blur being completely ignored. This also seems to apply
to other systems, though. See the following issue for more details:
https://bugs.chromium.org/p/chromium/issues/detail?id=1129838

Making the background opaque using rgba seems to fix the problem.

7 files changed, 7 insertions, 14 deletions

diff --git a/themes/compact.css b/themes/compact.css
index ccd6ef76c..d462892db 100644
--- a/themes/compact.css
+++ b/themes/compact.css
@@ -1475,8 +1475,7 @@ body.ttrss_utility hr {
   box-shadow: 0 1px 1px -1px rgba(0, 0, 0, 0.1);
   border: 0 solid #ddd;
   border-bottom-width: 1px;
-  background: white ! important;
-  opacity: 0.9;
+  background: rgba(255, 255, 255, 0.9) ! important;
   backdrop-filter: blur(6px);
 }
 body.ttrss_prefs {
diff --git a/themes/compact_night.css b/themes/compact_night.css
index 6b072e510..8b1cd17bc 100644
--- a/themes/compact_night.css
+++ b/themes/compact_night.css
@@ -1475,8 +1475,7 @@ body.ttrss_utility hr {
   box-shadow: 0 1px 1px -1px rgba(0, 0, 0, 0.1);
   border: 0 solid #222;
   border-bottom-width: 1px;
-  background: #333 ! important;
-  opacity: 0.9;
+  background: rgba(51, 51, 51, 0.9) ! important;
   backdrop-filter: blur(6px);
 }
 body.ttrss_prefs {
diff --git a/themes/light-high-contrast.css b/themes/light-high-contrast.css
index 18fc67f6a..77f3def7e 100644
--- a/themes/light-high-contrast.css
+++ b/themes/light-high-contrast.css
@@ -1475,8 +1475,7 @@ body.ttrss_utility hr {
   box-shadow: 0 1px 1px -1px rgba(0, 0, 0, 0.1);
   border: 0 solid #ddd;
   border-bottom-width: 1px;
-  background: white ! important;
-  opacity: 0.9;
+  background: rgba(255, 255, 255, 0.9) ! important;
   backdrop-filter: blur(6px);
 }
 body.ttrss_prefs {
diff --git a/themes/light.css b/themes/light.css
index 475e4dbbf..8367b07cc 100644
--- a/themes/light.css
+++ b/themes/light.css
@@ -1475,8 +1475,7 @@ body.ttrss_utility hr {
   box-shadow: 0 1px 1px -1px rgba(0, 0, 0, 0.1);
   border: 0 solid #ddd;
   border-bottom-width: 1px;
-  background: white ! important;
-  opacity: 0.9;
+  background: rgba(255, 255, 255, 0.9) ! important;
   backdrop-filter: blur(6px);
 }
 body.ttrss_prefs {
diff --git a/themes/light/cdm.less b/themes/light/cdm.less
index 4cbfa1d28..6bb3378c1 100644
--- a/themes/light/cdm.less
+++ b/themes/light/cdm.less
@@ -325,8 +325,7 @@
 			box-shadow : 0 1px 1px -1px rgba(0,0,0,0.1);
 			border: 0 solid @border-default;
 			border-bottom-width: 1px;
-			background : @default-bg ! important;
-			opacity: 0.9;
+			background : fade(@default-bg, 90%) ! important;
 			backdrop-filter: blur(6px);
 		}
 	}
diff --git a/themes/night.css b/themes/night.css
index 24288e149..447ca6f7f 100644
--- a/themes/night.css
+++ b/themes/night.css
@@ -1476,8 +1476,7 @@ body.ttrss_utility hr {
   box-shadow: 0 1px 1px -1px rgba(0, 0, 0, 0.1);
   border: 0 solid #222;
   border-bottom-width: 1px;
-  background: #333 ! important;
-  opacity: 0.9;
+  background: rgba(51, 51, 51, 0.9) ! important;
   backdrop-filter: blur(6px);
 }
 body.ttrss_prefs {
diff --git a/themes/night_blue.css b/themes/night_blue.css
index 209484935..7a6ce2b69 100644
--- a/themes/night_blue.css
+++ b/themes/night_blue.css
@@ -1476,8 +1476,7 @@ body.ttrss_utility hr {
   box-shadow: 0 1px 1px -1px rgba(0, 0, 0, 0.1);
   border: 0 solid #222;
   border-bottom-width: 1px;
-  background: #333 ! important;
-  opacity: 0.9;
+  background: rgba(51, 51, 51, 0.9) ! important;
   backdrop-filter: blur(6px);
 }
 body.ttrss_prefs {