Address 'Ask Us' feedback from UXWS

Why these changes are being introduced:

Darcy suggested changing the color, spacing, and size of the chat
icon.

Relevant ticket(s):

* [GDT-129](https://mitlibraries.atlassian.net/browse/GDT-129)

How this addresses that need:

This applies the suggested changes.

Side effects of this change:

I'd originally intended to move the `view-md` and `view-lg` rules
to the `layouts` partial, but opted against it since those are
only used for this element. I'd be happy to make that change, though,
if the reviewer feels otherwise.

Author: jazairi

app/assets/stylesheets/partials/_panels.scss

@@ -82,9 +82,11 @@
   a {
     margin-top: 0.5rem;
     &:after {
-      padding-left: 1rem;
       font-family: FontAwesome;
+      font-size: $fs-base;
+      color: $gray-l1;
       content: '\f075';
+      padding-left: .8rem;
     }
   }
   &.view-md {