Changed "Choose a user" to "Click on a user to log in".

- Set the width of .login-page-header to 100% to make it responsive on
smaller screens. Previously, the header went off screen for screen
widths <360 px.

Tweaked by tabbott to remove unnecessary translation tags.

Fixes #4106.

static/styles/portico.css

@@ -732,6 +732,10 @@ a.bottom-signup-button {
     margin-bottom: 50px;
 }
 
+.login-page-header {
+    width: 100%;
+}
+
 .login-page-subheader {
     font-weight: 300;
     font-size: 24px;

templates/zerver/login.html

@@ -44,7 +44,7 @@ autofocus('#id_username');
     {% if dev_auth_enabled %}
     <h3 class="login-page-header">{{ _('Development login') }}</h3>
     {% if not password_auth_enabled %}
-    <h4 class="login-page-subheader">{{ _('Choose a user:') }}</h4>
+    <h4 class="login-page-subheader">Click on a user to log in!</h4>
     {% endif %}
     {% else %}
     <h3 class="login-page-header">{{ _('You look familiar.') }}</h3>