Fix position of login buttons on mobile

src/invidious/views/login.ecr

@@ -7,10 +7,10 @@
     <div class="pure-u-1 pure-u-md-3-5">
         <div class="h-box">
             <div class="pure-g">
-                <div class="pure-u-1 pure-u-md-1-2">
+                <div class="pure-u-1-2">
                     <a class="pure-button <% if account_type == "google" %>pure-button-disabled<% end %>" href="/login">Login to Google</a>
                 </div>
-                <div class="pure-u-1 pure-u-md-1-2">
+                <div class="pure-u-1-2">
                     <a class="pure-button <% if account_type == "invidious" %>pure-button-disabled<% end %>" href="/login?type=invidious">Login/Register</a>
                 </div>
             </div>