panel: Remove panel translucency

Since commit 447bf55e45 we turn the top bar translucent when
free-floating. While this looks fancy and reduces the appearance
of cutting into the available screen space, it has also had a
negative effect on legibility.

Nobody stepped up to address those issues in two years, so revert
back to the fully opaque top bar.

https://gitlab.gnome.org/GNOME/gnome-shell/issues/408

data/theme/gnome-shell-sass/_common.scss

@@ -729,9 +729,7 @@ StScrollBar {
 /* TOP BAR */
 
 #panel {
-  background-color: rgba(0, 0, 0, 0.35);
-  /* transition from solid to transparent */
-  transition-duration: 500ms;
+  background-color: black;
   font-weight: bold;
   height: 1.86em;
   font-feature-settings: "tnum";
@@ -748,7 +746,7 @@ StScrollBar {
 
   .panel-corner {
     -panel-corner-radius: $panel-corner-radius;
-    -panel-corner-background-color: rgba(0, 0, 0, 0.35);
+    -panel-corner-background-color: black;
     -panel-corner-border-width: 2px;
     -panel-corner-border-color: transparent;
 
@@ -767,9 +765,7 @@ StScrollBar {
     -natural-hpadding: 12px;
     -minimum-hpadding: 6px;
     font-weight: bold;
-    color: #eee;
-    text-shadow: 0px 1px 2px rgba(0, 0, 0, 0.9);
-    transition-duration: 100ms;
+    color: #ccc;
 
     .app-menu-icon {
       -st-icon-style: symbolic;
@@ -778,21 +774,8 @@ StScrollBar {
       //dimensions of the icon are hardcoded
     }
 
-    .system-status-icon,
-    .app-menu-icon > StIcon,
-    .popup-menu-arrow {
-      icon-shadow: 0px 1px 2px rgba(0, 0, 0, 0.9);
-    }
-
     &:hover {
       color: lighten($fg_color, 10%);
-      text-shadow: 0px 1px 6px rgba(0, 0, 0, 1);
-
-      .system-status-icon,
-      .app-menu-icon > StIcon,
-      .popup-menu-arrow {
-        icon-shadow: 0px 1px 6px rgba(0, 0, 0, 1);
-      }
     }
 
     &:active, &:overview, &:focus, &:checked {
@@ -801,8 +784,6 @@ StScrollBar {
       background-color: rgba(0, 0, 0, 0.01);
       box-shadow: inset 0 -2px 0px lighten($selected_bg_color,5%);
       color: lighten($fg_color,10%);
-
-      & > .system-status-icon { icon-shadow: black 0 2px 2px; }
     }
 
     .system-status-icon { icon-size: 1.09em; padding: 0 5px; }
@@ -827,31 +808,6 @@ StScrollBar {
   .screencast-indicator { color: $warning_color; }
 
   .remote-access-indicator { color: $warning_color; }
-
-  &.solid {
-    background-color: black;
-    /* transition from transparent to solid */
-    transition-duration: 300ms;
-
-    .panel-corner {
-      -panel-corner-background-color: black;
-    }
-
-    .panel-button {
-      color: #ccc;
-      text-shadow: none;
-
-      &:hover, &:active, &:overview, &:focus, &:checked {
-        color: lighten($fg_color, 10%);
-      }
-    }
-
-    .system-status-icon,
-    .app-menu-icon > StIcon,
-    .popup-menu-arrow {
-      icon-shadow: none;
-    }
-  }
 }
 
   // calendar popover