list 2FA providers as buttons

core/css/styles.css

@@ -38,8 +38,11 @@ body {
 
 .two-factor-provider {
 	text-align: center;
-	width: 100%;
+	width: 258px !important;
 	display: inline-block;
+	margin-bottom: 0 !important;
+	background-color: rgba(0,0,0,0.3) !important;
+	border: none !important;
 }
 
 a.two-factor-cancel {

core/templates/twofactorselectchallenge.php

@@ -1,11 +1,11 @@
 <div class="warning">
-	<h2 class="two-factor-header"><?php p($l->t('Two-step verification')) ?></h2>
-	<p><?php p($l->t('Enhanced security has been enabled for your account. Please authenticate using a second factor.')) ?></p>
+	<h2 class="two-factor-header"><?php p($l->t('Two-factor authentication')) ?></h2>
+	<p><?php p($l->t('Enhanced security is enabled for your account. Please authenticate using a second factor.')) ?></p>
 	<p>
 		<ul>
 			<?php foreach ($_['providers'] as $provider): ?>
 				<li>
-					<a class="two-factor-provider"
+					<a class="button two-factor-provider"
 					   href="<?php p(\OC::$server->getURLGenerator()->linkToRoute('core.TwoFactorChallenge.showChallenge',
 										[
 											'challengeProviderId' => $provider->getId(),

core/templates/twofactorshowchallenge.php

@@ -12,7 +12,7 @@ $template = $_['template'];
 <div class="warning">
 		<h2 class="two-factor-header"><?php p($provider->getDisplayName()); ?></h2>
 		<?php if ($error): ?>
-		<p><?php p($l->t('An error occured while verifying the token')); ?></p>
+		<p><strong><?php p($l->t('Error while validating your second factor')); ?></strong></p>
 		<?php endif; ?>
 		<?php print_unescaped($template); ?>
 </div>