Improve legibility of panel close buttons

Author: jaygeorge

resources/css/core/layout.css

@@ -349,6 +349,8 @@ main.nav-closed {
         height: initial;
         cursor: pointer;
         padding: 1rem;
+        background: hsl(0deg 0% 100% / 50%);
+        backdrop-filter: blur(10px);
         & svg {
             font-size: 1rem;
             inline-size: unset;
@@ -382,6 +384,9 @@ main.nav-closed {
 
     .left-panel-popover__close-button {
         left: max(11rem, 33.33%);
+        border-end-start-radius: 0;
+        border-start-end-radius: 0;
+        border-start-start-radius: 0;
     }
 }
 
@@ -415,6 +420,8 @@ main.nav-closed {
 
     .right-panel-popover__close-button {
         right: max(18rem, 33.33%);
+        border-start-end-radius: 0;
+        border-end-end-radius: 0;
     }
 }