MDL-85338 message: make messaging drawer responsive to sticky footer.

Co-authored-by: David Woloszyn <[email protected]>

public/theme/boost/scss/moodle/sticky-footer.scss

@@ -14,7 +14,7 @@ body {
     height: $stickyfooter-height;
     bottom: calc(#{$stickyfooter-height} * -1);
     transition: bottom .5s;
-    z-index: $zindex-fixed;
+    z-index: $zindex-sticky;
     box-shadow: 0 0 1rem rgba($black, .15);
     font-size: calc(#{$font-size-base} * 1.10);
     // Adjust sticky footer width to the main content area.

public/theme/boost/style/moodle.css

@@ -38456,7 +38456,7 @@ body {
   height: max(80px, 0.9375rem * 3);
   bottom: calc(max(80px, 0.9375rem * 3) * -1);
   transition: bottom 0.5s;
-  z-index: 1030;
+  z-index: 1020;
   box-shadow: 0 0 1rem rgba(0, 0, 0, 0.15);
   font-size: calc(0.9375rem * 1.10);
 }

public/theme/classic/style/moodle.css

@@ -38390,7 +38390,7 @@ body {
   height: max(80px, 0.9375rem * 3);
   bottom: calc(max(80px, 0.9375rem * 3) * -1);
   transition: bottom 0.5s;
-  z-index: 1030;
+  z-index: 1020;
   box-shadow: 0 0 1rem rgba(0, 0, 0, 0.15);
   font-size: calc(0.9375rem * 1.10);
 }