Minor code quality improvements

www/pages/setup0.html

@@ -18,7 +18,7 @@
 
     <div class="page-content">
 
-        <div class="row" style="justify-content: center;">
+        <div class="row justify-content-center">
             <div class="col-100 desktop-66">
                 <div class="card">
                     <div class="card-content card-content-padding text-align-center">
@@ -28,7 +28,7 @@
                 </div>
             </div>
         </div>
-        <div class="row" style="justify-content: center;">
+        <div class="row justify-content-center">
             <a class="col-100 tablet-50 desktop-33" href="/setup/1/giver">
                 <div class="card">
                     <div class="card-content card-content-padding text-align-center bg-color-green text-color-white">

www/pages/setup1.html

@@ -30,7 +30,7 @@
                                     <div class="item-inner">
                                         <div class="item-title item-floating-label">Username</div>
                                         <div class="item-input-wrap">
-                                            <input type="text" id="username" placeholder="" autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" />
+                                            <input type="text" id="username" placeholder="" autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" pattern="[a-z0-9]+" />
                                             <span class="input-clear-button"></span>
                                         </div>
                                     </div>