style: update GitHubButton styles for improved layout

- Added a margin of 1px to the GitHubButton for better spacing.
- Reduced font size from 1.05rem to 0.8rem for a more compact appearance.

Author: atyrode

src/frontend/src/ui/GitHubButton.scss

@@ -3,6 +3,7 @@
   align-items: center;
   justify-content: center;
   height: 2.75rem;
+  margin: 1px;
   padding: 0 1rem;
   border-radius: 0.5rem;
   margin-left: 0.275rem;
@@ -13,7 +14,7 @@
   font-weight: 500;
   transition: background 0.15s ease-in-out, border 0.15s ease-in-out;
   gap: 0.5rem;
-  font-size: 1.05rem;
+  font-size: 0.8rem;
   font-weight: 500;
   color: #c9c9c9;
   font-family: "Roboto", sans-serif;