Group the buttons

Grouping the buttons helps with fixing the issue that they
are aligned closer to each other on smaller screens.

For the same reason, the buttons are not qualified as 'btn-lg'.

Author: sivaraam

index.html

@@ -46,9 +46,10 @@ <h2>The App</h2>
         <p class="lead">
             The Commons Mobile App is a community maintained app that makes it easy to upload your pictures to Wikimedia Commons. The app can be installed on any Android device and uses your Commons user account to upload photos.
         </p>
-
-        <a class="btn btn-lg btn-outline-primary" role="button" href="https://f-droid.org/repository/browse/?fdid=fr.free.nrw.commons">F-Droid page</a>
-        <a class="btn btn-lg btn-outline-primary" role="button" href="https://play.google.com/store/apps/details?id=fr.free.nrw.commons">Google Play page</a>
+        <div class="btn-group">
+            <a class="btn btn-outline-primary" role="button" href="https://f-droid.org/repository/browse/?fdid=fr.free.nrw.commons">F-Droid page</a>
+            <a class="btn btn-outline-primary" role="button" href="https://play.google.com/store/apps/details?id=fr.free.nrw.commons">Google Play page</a>
+        </div>
     </div>
     <div class="section-divider"></div>
     <div class="container inner" id="community">
@@ -156,9 +157,9 @@ <h2>Photo Guidelines</h2>
     <div class="section-divider"></div>
     <footer class="inner container footer">
         <h2>Commons Mobile App</h2>
-        <div>
-            <a class="btn btn-lg btn-outline-primary" role="button" href="https://github.com/commons-app/apps-android-commons">Source code</a>
-            <a class="btn btn-lg btn-outline-primary" role="button" href="https://github.com/commons-app/apps-android-commons/issues">Report an issue</a>
+        <div class="btn-group">
+            <a class="btn btn-outline-primary" role="button" href="https://github.com/commons-app/apps-android-commons">Source code</a>
+            <a class="btn btn-outline-primary" role="button" href="https://github.com/commons-app/apps-android-commons/issues">Report an issue</a>
         </div>
 
         <div class="qr-code-div">