fix: only disable user-selection on sliders (#4354)

src/css/components/_layout.scss

@@ -21,8 +21,6 @@
   // Avoiding helvetica: issue #376
   font-family: $text-font-family;
 
-  @include user-select(none);
-
   // Fix for Firefox 9 fullscreen (only if it is enabled). Not needed when
   // checking fullScreenEnabled.
   &:-moz-full-screen { position: absolute; }

src/css/components/_slider.scss

@@ -4,6 +4,8 @@
   padding: 0;
   margin: 0 0.45em 0 0.45em;
 
+  @include user-select(none);
+
   @include background-color-with-alpha($secondary-background-color, $secondary-background-transparency);
 }