diff --git a/src/material/AppTopBar.css b/src/material/AppTopBar.css
index cf692eb..a79321c 100644
--- a/src/material/AppTopBar.css
+++ b/src/material/AppTopBar.css
@@ -1,20 +1,31 @@
 .AppTopBar {
-  & > .MuiToolbar-root {
+  &::before {
+    contain: strict;
+    content: "";
+    position: absolute;
+    top: 0;
+    left: 0;
+    right: 0;
+    height: var(--safe-area-inset-top, 0);
+    background-color: rgba(0, 0, 0, 0.2);
+  }
+
+  &>.MuiToolbar-root {
     padding-top: var(--safe-area-inset-top, 0px);
     gap: 8px;
 
-    & > button:first-child, & > .MuiButtonBase-root:first-child {
+    &>button:first-child,
+    &>.MuiButtonBase-root:first-child {
       margin-left: -0.15em;
     }
 
-    & > button:last-child, & > .MuiButtonBase-root:last-child {
+    &>button:last-child,
+    &>.MuiButtonBase-root:last-child {
       margin-right: -0.15em;
     }
 
-    & > .title {
+    &>.title {
       margin-top: -0.2ch;
     }
   }
-}
-
-
+}
\ No newline at end of file