Index: wp-signup.php
===================================================================
--- wp-signup.php	(revision 23495)
+++ wp-signup.php	(working copy)
@@ -46,16 +46,11 @@
 		.mu_register { width: 90%; margin:0 auto; }
 		.mu_register form { margin-top: 2em; }
 		.mu_register .error { font-weight:700; padding:10px; color:#333333; background:#FFEBE8; border:1px solid #CC0000; }
-		.mu_register input[type="submit"],
-			.mu_register #blog_title,
-			.mu_register #user_email,
-			.mu_register #blogname,
-			.mu_register #user_name { width:100%; font-size: 24px; margin:5px 0; }
 		.mu_register .prefix_address,
 			.mu_register .suffix_address {font-size: 18px;display:inline; }
 		.mu_register label { font-weight:700; font-size:15px; display:block; margin:10px 0; }
 		.mu_register label.checkbox { display:inline; }
-		.mu_register .mu_alert { font-weight:700; padding:10px; color:#333333; background:#ffffe0; border:1px solid #e6db55; }
+		.mu_register .mu_alert { font-weight:700; padding:10px; color:#333333; background:#ffffe0; border:1px solid #e6db55; margin-top: 2em; }
 	</style>
 	<?php
 }
@@ -163,15 +158,16 @@
 	if ( $errmsg = $errors->get_error_message('user_name') ) {
 		echo '<p class="error">'.$errmsg.'</p>';
 	}
-	echo '<input name="user_name" type="text" id="user_name" value="'. esc_attr($user_name) .'" maxlength="60" /><br />';
-	_e( '(Must be at least 4 characters, letters and numbers only.)' );
+	echo '<input name="user_name" type="text" id="user_name" value="'. esc_attr($user_name) .'" maxlength="60" />';
 	?>
+	<p class="mu-instructions"><?php esc_html_e('(Must be at least 4 characters, letters and numbers only.)'); ?></p>
 
 	<label for="user_email"><?php _e( 'Email&nbsp;Address:' ) ?></label>
 	<?php if ( $errmsg = $errors->get_error_message('user_email') ) { ?>
 		<p class="error"><?php echo $errmsg ?></p>
 	<?php } ?>
-	<input name="user_email" type="text" id="user_email" value="<?php  echo esc_attr($user_email) ?>" maxlength="200" /><br /><?php _e('We send your registration email to this address. (Double-check your email address before continuing.)') ?>
+	<input name="user_email" type="text" id="user_email" value="<?php  echo esc_attr($user_email) ?>" maxlength="200" />
+	<p class="mu-instructions"><?php esc_html_e('We send your registration email to this address. (Double-check your email address before continuing.)'); ?></p>
 	<?php
 	if ( $errmsg = $errors->get_error_message('generic') ) {
 		echo '<p class="error">' . $errmsg . '</p>';
Index: wp-content/themes/twentythirteen/style.css
===================================================================
--- wp-content/themes/twentythirteen/style.css	(revision 23495)
+++ wp-content/themes/twentythirteen/style.css	(working copy)
@@ -2171,14 +2171,15 @@
 
 
 /**
- * 5.12 Comments
+ * 5.12 Comments and Multisite front-end forms
  * ----------------------------------------------------------------------------
  */
 
 .comments-title,
 .comment-list,
 #reply-title,
-#respond #commentform {
+#respond #commentform,
+.mu_register {
 	margin: 0 auto;
 	max-width: 604px;
 	width: 100%;
@@ -2372,7 +2373,8 @@
 }
 
 .form-allowed-tags,
-.form-allowed-tags code {
+.form-allowed-tags code,
+.mu-instructions {
 	color: #7d7b6d;
 	font-size: 12px;
 }