diff --git a/README.md b/README.md
index 1ca0c6e..d88f2ba 100644
--- a/README.md
+++ b/README.md
@@ -17,7 +17,7 @@ your production-ready server of choice.
 
 ## Screenshots
 
-The index lists available UPS devices, along with their description,
+The index lists available UPS devices on each server, along with their description,
 status, and battery charge:
 
 ![Index](screenshots/ups_index.png "Index")
@@ -27,3 +27,5 @@ status indicator, as well as the values of all variables set on the
 device:
 
 ![UPS View](screenshots/ups_view.png "UPS View")
+
+Clicking on the power icon will return to the index page.
\ No newline at end of file
diff --git a/screenshots/ups_index.png b/screenshots/ups_index.png
index 3789a62..0b4f43c 100644
Binary files a/screenshots/ups_index.png and b/screenshots/ups_index.png differ
diff --git a/screenshots/ups_view.png b/screenshots/ups_view.png
index 2383263..a3ff508 100644
Binary files a/screenshots/ups_view.png and b/screenshots/ups_view.png differ
diff --git a/webnut/__init__.py b/webnut/__init__.py
index 83e98ae..0549098 100644
--- a/webnut/__init__.py
+++ b/webnut/__init__.py
@@ -8,10 +8,11 @@ def main(global_config, **settings):
     config = Configurator(settings=settings)
     config.include('pyramid_chameleon')
     config.add_static_view('static', 'static', cache_max_age=3600)
+    config.add_route("favicon", "/favicon.ico")
     config.add_route('home', '/')
     config.add_route('ups_view', '/{ups}')
     config.add_view('webnut.views.notfound',
-            renderer='webnut:templates/404.pt',
-            context='pyramid.exceptions.NotFound')
+                    renderer='webnut:templates/404.pt',
+                    context='pyramid.exceptions.NotFound')
     config.scan()
     return config.make_wsgi_app()
diff --git a/webnut/config.example.py b/webnut/config.example.py
index c3cd265..68c2d2b 100644
--- a/webnut/config.example.py
+++ b/webnut/config.example.py
@@ -1,6 +1,18 @@
 # User-defined configuration.
 # Rename this to config.py.
+
+# Single server configuration, backwards compatible:
+
 server = '127.0.0.1'
 port = 3493
 username = None
 password = None
+
+# Multi-server configuration:
+
+from .webnut import NUTServer
+
+servers = [
+    NUTServer('192.168.1.3', 3493, None, None),
+    NUTServer('192.168.1.6', 3493, None, None)
+]
diff --git a/webnut/static/favicon.ico b/webnut/static/favicon.ico
new file mode 100644
index 0000000..0af01ac
Binary files /dev/null and b/webnut/static/favicon.ico differ
diff --git a/webnut/templates/404.pt b/webnut/templates/404.pt
index 6734592..8891467 100644
--- a/webnut/templates/404.pt
+++ b/webnut/templates/404.pt
@@ -1,6 +1,5 @@
 <div metal:use-macro="view.layout">
     <div metal:fill-slot="content">
-            <br>
             <h3>404 Not Found</h3>
             Sorry, no UPS with that name exists.
     </div>
diff --git a/webnut/templates/index.pt b/webnut/templates/index.pt
index 8a62e3b..60d2ad7 100644
--- a/webnut/templates/index.pt
+++ b/webnut/templates/index.pt
@@ -1,29 +1,36 @@
 <div metal:use-macro="view.layout">
     <div metal:fill-slot="content">
-            <br>
             <table class="table table-striped table-hover" id="ups_table">
                 <thead>
                     <tr>
                         <th>Name</th>
+                        <th>Server</th>
                         <th>Description</th>
                         <th>Status</th>
                         <th>Battery</th>
+                        <th>Runtime</th>
                     </tr>
                 </thead>
                 <tbody>
                     <tr tal:repeat="ups ups_list">
                         <td>
-                            <a href="${request.route_url('ups_view', ups=ups)}">${ups}</a>
+                            <a title="${ups_list[ups]['name']} detail" href="${request.route_url('ups_view', ups=ups)}">${ups_list[ups]['name']}</a>
                         </td>
+                        <td>${ups_list[ups]['server']}</td>
                         <td>${ups_list[ups]['description']}</td>
                         <td>${ups_list[ups]['status']}</td>
-                        <td>${ups_list[ups]['battery']}%</td>
+                        <td>${ups_list[ups]['battery']}</td>
+                        <td>${ups_list[ups]['runtime']}</td>
                     </tr>
                 </tbody>
             </table>
 
-            <script type="text/javascript" charset="utf8" src="//cdn.datatables.net/1.10-dev/js/jquery.dataTables.min.js"></script>
-            <script type="text/javascript" charset="utf8" src="//cdn.datatables.net/plug-ins/28e7751dbec/integration/bootstrap/3/dataTables.bootstrap.js"></script>
+            <link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.1.1/css/bootstrap.min.css"/>
+            <link rel="stylesheet" type="text/css" href="https://cdn.datatables.net/1.10.24/css/dataTables.bootstrap4.min.css"/>
+            <script type="text/javascript" charset="utf8" src="https://code.jquery.com/jquery-3.3.1.min.js"></script>
+            <script type="text/javascript" charset="utf8" src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.1.1/js/bootstrap.min.js"></script>
+            <script type="text/javascript" charset="utf8" src="https://cdn.datatables.net/1.10.24/js/jquery.dataTables.min.js"></script>
+            <script type="text/javascript" charset="utf8" src="https://cdn.datatables.net/1.10.24/js/dataTables.bootstrap4.min.js"></script>
             <script type="text/javascript">
                 $(function(){
                     $("#ups_table").dataTable();
diff --git a/webnut/templates/layout.pt b/webnut/templates/layout.pt
index f564847..361653b 100644
--- a/webnut/templates/layout.pt
+++ b/webnut/templates/layout.pt
@@ -6,23 +6,25 @@
       metal:define-macro="layout">
 <head>
     <title>${title} - webNUT</title>
-    <link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.0.3/css/bootstrap.min.css"/>
-    <link rel="stylesheet" href="//netdna.bootstrapcdn.com/font-awesome/4.0.3/css/font-awesome.css"/>
-    <link rel="stylesheet" href="//cdn.datatables.net/plug-ins/28e7751dbec/integration/bootstrap/3/dataTables.bootstrap.css"/>
-    <script type="text/javascript" src="//code.jquery.com/jquery.min.js"></script>
-    <script type="text/javascript" src="//netdna.bootstrapcdn.com/bootstrap/3.0.3/js/bootstrap.min.js"></script>
+    <link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.15.2/css/all.css">
+    <link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.15.2/css/v4-shims.css">
+    <link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.1.1/css/bootstrap.min.css"/>
+    <link rel="stylesheet" type="text/css" href="https://cdn.datatables.net/1.10.24/css/dataTables.bootstrap4.min.css"/>    
+    <script type="text/javascript" charset="utf8" src="https://code.jquery.com/jquery-3.3.1.min.js"></script>
+    <script type="text/javascript" charset="utf8" src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.1.1/js/bootstrap.min.js"></script>
+    <script type="text/javascript" charset="utf8" src="https://cdn.datatables.net/1.10.24/js/jquery.dataTables.min.js"></script>
+    <script type="text/javascript" charset="utf8" src="https://cdn.datatables.net/1.10.24/js/dataTables.bootstrap4.min.js"></script>
 </head>
 <body>
 <div id="main">
-    <div class="col-sm-8 col-sm-offset-2 col-xs-12 col-xs-offset-0">
+    <div class="col-sm-8 offset-sm-2 col-xs-12 offset-xs-0 mt-3 mb-5">
         <div class="row">
-            <h2><i class="fa fa-power-off"></i> ${title}</h2>
+            <h2><a href="/" title="Device list"><i class="fa fa-power-off"></i></a>&nbsp;${title}</h2>
+        </div>
+        <div class="row mt-3">
             <div metal:define-slot="content">
             </div>
         </div>
-        <div class="row">
-            <br><br><br>
-        </div>
     </div>
 </div>
 </body>
diff --git a/webnut/templates/ups_view.pt b/webnut/templates/ups_view.pt
index bfc542e..fd3fd63 100644
--- a/webnut/templates/ups_view.pt
+++ b/webnut/templates/ups_view.pt
@@ -1,9 +1,15 @@
 <div metal:use-macro="view.layout">
     <div metal:fill-slot="content">
-            <strong>Status</strong>: ${ups_status}
-            <br>
-            <strong>Battery charge</strong>: ${ups_vars['battery.charge'][0]}%
-            <br>
+            <div class="col-sm-8 col-xs-8 pl-0 mb-2">
+                <div class="row">
+                    <div class="col-4"><strong>Status</strong>:</div>
+                    <div class="col-2">${ups_status}</div>
+                </div>
+                <div class="row">
+                    <div class="col-4"><strong>Battery charge</strong>:</div>
+                    <div class="col-2">${ups_battery}</div>
+                </div>
+            </div>
             <h3>UPS Variables</h3>
             <table class="table table-striped table-hover" id="var_table">
                 <thead>
@@ -11,6 +17,7 @@
                         <th>Name</th>
                         <th>Description</th>
                         <th>Value</th>
+                        <th>Writable</th>
                     </tr>
                 </thead>
                 <tbody>
@@ -18,12 +25,17 @@
                         <td>${var}</td>
                         <td>${ups_vars[var][1]}</td>
                         <td>${ups_vars[var][0]}</td>
+                        <td class="text-center">${ups_vars[var][2]}</td>
                     </tr>
                 </tbody>
             </table>
 
-            <script type="text/javascript" charset="utf8" src="//cdn.datatables.net/1.10-dev/js/jquery.dataTables.min.js"></script>
-            <script type="text/javascript" charset="utf8" src="//cdn.datatables.net/plug-ins/28e7751dbec/integration/bootstrap/3/dataTables.bootstrap.js"></script>
+            <link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.1.1/css/bootstrap.min.css"/>
+            <link rel="stylesheet" type="text/css" href="https://cdn.datatables.net/1.10.24/css/dataTables.bootstrap4.min.css"/>
+            <script type="text/javascript" charset="utf8" src="https://code.jquery.com/jquery-3.3.1.min.js"></script>
+            <script type="text/javascript" charset="utf8" src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.1.1/js/bootstrap.min.js"></script>
+            <script type="text/javascript" charset="utf8" src="https://cdn.datatables.net/1.10.24/js/jquery.dataTables.min.js"></script>
+            <script type="text/javascript" charset="utf8" src="https://cdn.datatables.net/1.10.24/js/dataTables.bootstrap4.min.js"></script>
             <script type="text/javascript">
                 $(function(){
                     $("#var_table").dataTable();
diff --git a/webnut/views.py b/webnut/views.py
index 7099136..acb533b 100644
--- a/webnut/views.py
+++ b/webnut/views.py
@@ -1,22 +1,45 @@
+import os
+
 from pyramid.exceptions import NotFound
 from pyramid.renderers import get_renderer
 from pyramid.view import view_config
+from pyramid.response import FileResponse
 
 from .webnut import WebNUT
+from .webnut import NUTServer
+
 from . import config
 
+
 class NUTViews(object):
     def __init__(self, request):
         self.request = request
         renderer = get_renderer("templates/layout.pt")
         self.layout = renderer.implementation().macros['layout']
-        self.webnut = WebNUT(config.server, config.port,
-                config.username, config.password)
+        # Backward compatible support for single server configuration
+        servers = []
+        if hasattr(config, 'servers'):
+            servers = config.servers
+        if (hasattr(config, 'server') and hasattr(config, 'port') and
+                hasattr(config, 'username') and hasattr(config, 'password')):
+            servers.append(NUTServer(config.server, config.port,
+                                     config.username, config.password))
+        self.webnut = WebNUT(servers)
+
+    @view_config(route_name="favicon")
+    def favicon_view(self):
+        here = os.path.dirname(__file__)
+        icon = os.path.join(here, "static", "favicon.ico")
+        return FileResponse(icon, request=self.request)
 
     @view_config(route_name='home', renderer='templates/index.pt')
     def home(self):
-        return dict(title='UPS Devices',
-                ups_list=self.webnut.get_ups_list())
+        ups_list = self.webnut.get_ups_list()
+        # Update some list values with custom HTML rendering.
+        for (_, ups_vars) in ups_list.items():
+            ups_vars['status'] = self._ups_status(ups_vars['status'])
+            ups_vars['battery'] = self._ups_battery(ups_vars['battery'])
+        return dict(title='UPS Devices', ups_list=ups_list)
 
     @view_config(route_name='ups_view', renderer='templates/ups_view.pt')
     def ups_view(self):
@@ -24,11 +47,84 @@ def ups_view(self):
         try:
             ups_name = self.webnut.get_ups_name(ups)
             ups_vars = self.webnut.get_ups_vars(ups)
-            return dict(title=ups_name, ups_vars=ups_vars[0],
-                    ups_status=ups_vars[1])
+            ups_status = ups_vars.get('ups.status', ('Unknown', ''))[0]
+            ups_battery = int(ups_vars.get('battery.charge', (0, ''))[0])
+            # Update vars with custom HTML rendering.
+            for (k, v) in ups_vars.items():
+                ups_vars[k] = (v[0], v[1], self._ups_var_writable(v[2]))
+            return dict(title=ups_name,
+                        ups_vars=ups_vars,
+                        ups_status=self._ups_status(ups_status),
+                        ups_battery=self._ups_battery(ups_battery))
         except KeyError:
             raise NotFound
 
+    def _ups_var_writable(self, writable: bool):
+
+        class ReadWrite(object):
+            # Allows Chameleon to print unescaped HTML.
+            def __init__(self, writable: bool):
+                self.writable = writable
+
+            def __html__(self):
+                if not writable:
+                    return ''
+                return '''<i class="fas fa-pen-square fa-lg text-success" title="Writable"></i>'''
+
+        return ReadWrite(writable)
+
+    def _ups_status(self, status: str):
+
+        class Status(object):
+            # Allows Chameleon to print unescaped HTML.
+            def __init__(self, icon, color, title):
+                self.icon = icon
+                self.color = color
+                self.title = title
+
+            def __html__(self):
+                return '''
+                <i class="fa fa-{0}" style="color:{1}" title="{2}"></i>
+                '''.format(self.icon, self.color, self.title)
+
+        if status.startswith('OL'):
+            return Status('check', 'green', 'Online')
+        elif status.startswith('OB'):
+            return Status('warning', 'orange', 'On Battery')
+        elif status.startswith('LB'):
+            return Status('warning', 'red', 'Low Battery')
+        return Status('unknown', 'black', 'Unknown')
+
+    def _ups_battery(self, charge: int):
+
+        class Status(object):
+            # Allows Chameleon to print unescaped HTML.
+            def __init__(self, charge, color):
+                self.charge = charge
+                self.color = color
+
+            def __html__(self):
+                height = 20
+                return '''
+                <div class="progress position-relative" style="height:{0}px;background-color:silver;line-height:{0}px;">
+                    <div class="progress-bar {1}"
+                        style="width:{2}%;color:black"
+                        role="progressbar";
+                        aria-valuenow="{2}"
+                        aria-valuemin="0"
+                        aria-valuemax="100"></div>
+                    <span title="{2}%" class="justify-content-center align-middle d-flex position-absolute w-100">{2}%</span>
+                </div>
+                '''.format(height, self.color, self.charge)
+
+        if charge > 90:
+            return Status(charge, 'bg-success')
+        elif charge > 60:
+            return Status(charge, 'bg-warning')
+        else:
+            return Status(charge, 'bg-danger')
+
+
 def notfound(request):
     request.response.status = 404
     return dict(title='No Such UPS')
diff --git a/webnut/webnut.py b/webnut/webnut.py
index 981d7e8..5ff7f5f 100644
--- a/webnut/webnut.py
+++ b/webnut/webnut.py
@@ -1,73 +1,99 @@
 import nut2
+import datetime
 
+# Some NUT variables don't have descriptions. This adds additional
+# descriptions for variables that return "Description unavailable".
+DEFAULT_DESCRIPTIONS = {
+    "device.mfr": "Device manufacturer",
+    "device.model": "Device model",
+    "device.serial": "Device serial number",
+    "device.type": "Device type",
+    # "driver.parameter.mode": "",
+    "driver.parameter.pollfreq": "Polling frequency",
+    # "driver.parameter.pollinterval": "",
+    # "driver.parameter.port": "",
+    # "driver.parameter.synchronous": "",
+    "driver.version.data": "Driver version - Additional data",
+}
 
-class WebNUT(object):
-    def __init__(self, server='127.0.0.1', port=3493, username=None, password=None):
-        self.server = server
+
+class NUTServer(object):
+    def __init__(self, host='127.0.0.1', port=3493, username=None, password=None):
+        self.host = host
         self.port = port
         self.username = username
         self.password = password
 
+
+class WebNUT(object):
+    def __init__(self, servers=[]):
+        self.servers = dict()
+        for s in servers:
+            self.servers[s.host] = s
+
     def get_ups_list(self):
+        """Return a dict containing a dict of properties for each UPS."""
         try:
-            with nut2.PyNUTClient(host=self.server, port=self.port,
-                    login=self.username, password=self.password) as client:
-                ups_dict = client.list_ups()
-                ups_list = dict()
-                for ups in ups_dict:
-                    try:
-                        ups_vars = client.list_vars(ups)
-                    except nut2.PyNUTError:
-                        continue
+            ups_list = dict()
+            for k, v in self.servers.items():
+                with nut2.PyNUTClient(host=v.host, port=v.port,
+                                      login=v.username, password=v.password) as client:
+                    ups_dict = client.list_ups()
+                    for ups in ups_dict:
+                        try:
+                            ups_vars = client.list_vars(ups)
+                        except nut2.PyNUTError:
+                            continue
 
-                    ups_list[ups] = {
-                        'description': client.description(ups),
-                        'status': self._get_ups_status(ups_vars),
-                        'battery': ups_vars['battery.charge'],
-                    }
-                return ups_list
+                        runtime = str(datetime.timedelta(
+                            seconds=int(ups_vars.get('battery.runtime', 0))))
+                        ups_list[ups+'@'+v.host] = {
+                            'name': ups,
+                            'server': k,
+                            'description': client.description(ups),
+                            'status': ups_vars.get('ups.status', 'Unknown'),
+                            'battery': int(ups_vars.get('battery.charge', 0)),
+                            'runtime': runtime,
+                        }
+            return ups_list
         except nut2.PyNUTError:
             return dict()
 
-    def get_ups_name(self, ups):
+    def get_ups_name(self, ups: str):
+        """Return the name of a UPS."""
         try:
-            with nut2.PyNUTClient(host=self.server, port=self.port,
-                    login=self.username, password=self.password) as client:
-                return client.list_ups()[ups]
+            (ups_name, ups_server) = self._get_ups(ups)
+            if not ups_name:
+                return ''
+            server = self.servers[ups_server]
+            with nut2.PyNUTClient(host=server.host, port=server.port,
+                                  login=server.username, password=server.password) as client:
+                return client.list_ups()[ups_name]
         except nut2.PyNUTError:
-            return dict()
+            return ''
 
-    def get_ups_vars(self, ups):
+    def get_ups_vars(self, ups: str):
+        """Returns a dict containing a (value, description) tuple for each UPS variable."""
+        (ups_name, ups_server) = self._get_ups(ups)
+        if not ups_name:
+            return dict()
+        server = self.servers[ups_server]
         try:
-            with nut2.PyNUTClient(host=self.server, port=self.port,
-                    login=self.username, password=self.password) as client:
-                ups_vars = client.list_vars(ups)
+            with nut2.PyNUTClient(host=server.host, port=server.port,
+                                  login=server.username, password=server.password) as client:
+                ups_vars = client.list_vars(ups_name)
+                ups_rw_vars = client.list_rw_vars(ups_name)
                 for var in ups_vars:
-                    ups_vars[var] = (ups_vars[var],
-                            client.var_description(ups, var))
-                return (ups_vars, self._get_ups_status(ups_vars))
+                    desc = client.var_description(ups_name, var)
+                    if desc == "Description unavailable" and var in DEFAULT_DESCRIPTIONS:
+                        desc = DEFAULT_DESCRIPTIONS[var]
+                    ups_vars[var] = (ups_vars[var], desc, var in ups_rw_vars)
+                return ups_vars
         except nut2.PyNUTError:
-            return (dict(), str())
-
-
-    def _get_ups_status(self, ups_vars):
-        status = ups_vars['ups.status']
-        if type(status) == tuple:
-            status = status[0]
-
-        class Status(object):
-            # Allows Chameleon to print unescaped HTML.
-            def __init__(self, icon, color, title):
-                self.icon = icon
-                self.color = color
-                self.title = title
-
-            def __html__(self):
-                return '<i class="fa fa-%s" style="color: %s" title="%s"></i>' % (
-                        self.icon, self.color, self.title)
+            return dict()
 
-        if status.startswith('OL'):
-            status = Status('check', 'green', 'Online')
-        elif status.startswith('OB'):
-            status = Status('warning', 'orange', 'On Battery')
-        return status
+    def _get_ups(self, ups: str):
+        id = ups.split('@')
+        if len(id) != 2:
+            return (None, None)
+        return (id[0], id[1])