diff --git a/demo/simple_test.py b/demo/simple_test.py
index a1f320e..c2b2813 100755
--- a/demo/simple_test.py
+++ b/demo/simple_test.py
@@ -28,7 +28,7 @@ dot = Dot()
 dot.x_labels = map(str, range(4))
 
 dot.add('a', [1, lnk(3, 'Foo'), 5, 3])
-dot.add('b', [2, -2, 0, 2])
+dot.add('b', [2, 2, 0, 2])
 dot.add('c', [5, 1, 5, lnk(3, 'Bar')])
 dot.add('d', [5, 5, lnk(0, 'Babar'), 3])
 
@@ -45,7 +45,8 @@ bar.add('1234', [
 
 bar.add('4321', [40, {'value': 30, 'label': 'Thirty', 'xlink': 'http://google.com?q=30'}, 20, 10])
 bar.x_labels = map(str, range(1, 5))
-
+bar.logarithmic = True
+bar.zero = 1
 # bar.included_js = []
 # bar.external_js = [
     # 'http://localhost:7575/svg.jquery.js',
@@ -163,7 +164,7 @@ config.x_labels = (
     'black', 'red', 'blue', 'yellow', 'orange', 'green', 'white')
 # config.interpolate = 'nearest'
 radar = Radar(config)
-radar.add('test', [1, 4, lnk(10), 5, None, -2, 5])
+radar.add('test', [1, 4, lnk(10), 5, None, 2, 5])
 radar.add('test2', [10, 2, 0, 5, 1, 9, 4])
 
 radar.title = "Radar test"
diff --git a/pygal/config.py b/pygal/config.py
index 28bb737..0fd2410 100644
--- a/pygal/config.py
+++ b/pygal/config.py
@@ -21,7 +21,6 @@
 Config module with all options
 """
 
-import os
 from pygal.style import DefaultStyle
 
 
@@ -40,11 +39,10 @@ class Config(object):
     human_readable = False
     #: Display values in logarithmic scale
     logarithmic = False
-    #: If set to a filename, this will replace the default css
-    base_css = None
-    #: or default js
-    included_js = []
-    external_js = [
+    #: List of css file, can be an absolute file path or an external link
+    css = ['style.css', 'graph.css']  # Relative path to pygal css
+    #: List of js file, can be a filepath or an external link
+    js = [
         'https://raw.github.com/Kozea/pygal.js/master/svg.jquery.js',
         'https://raw.github.com/Kozea/pygal.js/master/pygal-tooltips.js'
     ]
diff --git a/pygal/css/base.css b/pygal/css/base.css
new file mode 100644
index 0000000..5391838
--- /dev/null
+++ b/pygal/css/base.css
@@ -0,0 +1,48 @@
+/*
+ * This file is part of pygal
+ *
+ * A python svg graph plotting library
+ * Copyright © 2012 Kozea
+
+ * This library is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Lesser General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ *
+ * This library is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with pygal. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/* 
+ * Font-sizes from config, override with care
+ */
+
+.title {
+  font-family: monospace;
+  font-size: {{ font_sizes.title }};
+}
+
+.legends .legend text {
+  font-family: monospace;
+  font-size: {{ font_sizes.legend }};
+}
+
+.axis text {
+  font-family: monospace;
+  font-size: {{ font_sizes.label }};
+}
+
+.series text {
+  font-family: monospace;
+  font-size: {{ font_sizes.value }};
+}
+
+#tooltip text {
+  font-family: monospace;
+  font-size: {{ font_sizes.tooltip }};
+}
diff --git a/pygal/css/graph.css b/pygal/css/graph.css
index 668d0f5..6e65b12 100644
--- a/pygal/css/graph.css
+++ b/pygal/css/graph.css
@@ -18,30 +18,7 @@
  * along with pygal. If not, see <http://www.gnu.org/licenses/>.
 */
 
-svg {
-  background-color: {{ style.background }};
-}
-
-svg * {
-  -webkit-transition: {{ style.transition }};
-  -moz-transition: {{ style.transition }};
-  transition: {{ style.transition }};
-}
-
-.graph > .background {
-  fill: {{ style.background }};
-}
-
-.plot > .background {
-  fill: {{ style.plot_background }};
-}
-
-.graph {
-  fill: {{ style.foreground }};
-}
-
 text.no_data {
-  fill: {{ style.foreground_light }};
   text-anchor: middle;
 }
 
@@ -54,29 +31,14 @@ text.no_data {
 }
 
 .title {
-  fill: {{ style.foreground_light }};
-  font-size: {{ font_sizes.title }};
   text-anchor: middle;
 }
 
 .legends .legend text {
-  font-family: monospace;
-  font-size: {{ font_sizes.legend }};
-  fill: {{ style.foreground }};
   fill-opacity: 1;
 }
 
-.legends .legend:hover text {
-  fill: {{ style.foreground_light }};
-}
-
-.axis text {
-  font-size: {{ font_sizes.label }};
-  font-family: sans;
-}
-
 .axis.x text {
-  font-family: monospace;
   text-anchor: middle;
 }
 
@@ -85,7 +47,6 @@ text.no_data {
 }
 
 .axis.y text {
-  font-family: monospace;
   text-anchor: end;
 }
 
@@ -93,26 +54,19 @@ text.no_data {
   font-size: 50%;
 }
 
-.axis .line {
-  stroke: {{ style.foreground_light }};
-}
-
 .axis .guide.line {
-  stroke: {{ style.foreground_dark }};
   stroke-dasharray: 4,4;
 }
 
 .axis .major.line {
-  stroke: {{ style.foreground }};
   stroke-dasharray: 6,6;
 }
 .axis text.major {
   stroke-width: 0.5px;
-  stroke: {{ style.foreground_light }};
-  fill: {{ style.foreground_light }};
 }
 
-.axis.{{ hidden }} .guide.line {
+.horizontal .axis.y .guide.line,
+.vertical .axis.x .guide.line {
   opacity: 0;
 }
 
@@ -120,12 +74,10 @@ text.no_data {
 .line-graph .axis.x .guides:hover .guide.line,
 .stackedline-graph .axis.x .guides:hover .guide.line,
 .xy-graph .axis.x .guides:hover .guide.line {
-  stroke: {{ style.foreground_light }};
   opacity: 1;
 }
 
 .axis .guides:hover text {
-  fill: {{ style.foreground_light }};
   opacity: 1;
 }
 
@@ -133,14 +85,6 @@ text.no_data {
   fill: none;
 }
 
-.reactive {
-  fill-opacity: {{ style.opacity }};
-}
-
-.reactive.active, .active .reactive {
-  fill-opacity:  {{ style.opacity_hover }};
-}
-
 .dot {
   stroke-width: 1px;
   fill-opacity: 1;
@@ -151,9 +95,7 @@ text.no_data {
 }
 
 .series text {
-  font-size: {{ font_sizes.value }};
   stroke: none;
-  fill: {{ style.foreground_light }};
 }
 
 .series text.active {
@@ -162,14 +104,10 @@ text.no_data {
 
 #tooltip rect {
   fill-opacity: 0.8;
-  fill: {{ style.plot_background }};
-  stroke: {{ style.foreground_light }};
 }
 
 #tooltip text {
   fill-opacity: 1;
-  fill: {{ style.foreground_light }};
-  font-size: {{ font_sizes.tooltip }};
 }
 
 #tooltip text tspan.label {
@@ -179,5 +117,3 @@ text.no_data {
 a:visited {
   fill: none;
 }
-
-{{ style.colors }}
diff --git a/pygal/css/style.css b/pygal/css/style.css
new file mode 100644
index 0000000..25824b9
--- /dev/null
+++ b/pygal/css/style.css
@@ -0,0 +1,112 @@
+/*
+ * This file is part of pygal
+ *
+ * A python svg graph plotting library
+ * Copyright © 2012 Kozea
+
+ * This library is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Lesser General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ *
+ * This library is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with pygal. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/* 
+ * Styles from config
+ */
+
+svg {
+  background-color: {{ style.background }};
+}
+
+svg * {
+  -webkit-transition: {{ style.transition }};
+  -moz-transition: {{ style.transition }};
+  transition: {{ style.transition }};
+}
+
+.graph > .background {
+  fill: {{ style.background }};
+}
+
+.plot > .background {
+  fill: {{ style.plot_background }};
+}
+
+.graph {
+  fill: {{ style.foreground }};
+}
+
+text.no_data {
+  fill: {{ style.foreground_light }};
+}
+
+.title {
+  fill: {{ style.foreground_light }};
+}
+
+.legends .legend text {
+  fill: {{ style.foreground }};
+}
+
+.legends .legend:hover text {
+  fill: {{ style.foreground_light }};
+}
+
+.axis .line {
+  stroke: {{ style.foreground_light }};
+}
+
+.axis .guide.line {
+  stroke: {{ style.foreground_dark }};
+}
+
+.axis .major.line {
+  stroke: {{ style.foreground }};
+}
+
+.axis text.major {
+  stroke: {{ style.foreground_light }};
+  fill: {{ style.foreground_light }};
+}
+
+.axis.y .guides:hover .guide.line,
+.line-graph .axis.x .guides:hover .guide.line,
+.stackedline-graph .axis.x .guides:hover .guide.line,
+.xy-graph .axis.x .guides:hover .guide.line {
+  stroke: {{ style.foreground_light }};
+}
+
+.axis .guides:hover text {
+  fill: {{ style.foreground_light }};
+}
+
+.reactive {
+  fill-opacity: {{ style.opacity }};
+}
+
+.reactive.active, .active .reactive {
+  fill-opacity:  {{ style.opacity_hover }};
+}
+
+.series text {
+  fill: {{ style.foreground_light }};
+}
+
+#tooltip rect {
+  fill: {{ style.plot_background }};
+  stroke: {{ style.foreground_light }};
+}
+
+#tooltip text {
+  fill: {{ style.foreground_light }};
+}
+
+{{ style.colors }}
diff --git a/pygal/graph/bar.py b/pygal/graph/bar.py
index d685227..96be243 100644
--- a/pygal/graph/bar.py
+++ b/pygal/graph/bar.py
@@ -68,9 +68,9 @@ class Bar(Graph):
             padding = .1 * width
             inner_width = width - 2 * padding
             if self.horizontal:
-                height = self.view.x(0) - y
+                height = self.view.x(self.zero) - y
             else:
-                height = self.view.y(0) - y
+                height = self.view.y(self.zero) - y
             if stack_vals == None:
                 bar_width = inner_width / len(self.series)
                 bar_padding = .1 * bar_width
diff --git a/pygal/graph/base.py b/pygal/graph/base.py
index b87f90c..9fa7f94 100644
--- a/pygal/graph/base.py
+++ b/pygal/graph/base.py
@@ -23,7 +23,7 @@ Base for pygal charts
 
 from __future__ import division
 import io
-from pygal.serie import Serie, Value
+from pygal.serie import Serie, Value, PositiveValue
 from pygal.view import Margin, Box
 from pygal.util import get_text_box, get_texts_box, cut, rad, humanize
 from pygal.svg import Svg
@@ -60,6 +60,9 @@ class BaseGraph(object):
         """(Re-)Init the graph"""
         self.margin = Margin(*([20] * 4))
         self._box = Box()
+        if self.logarithmic and self.zero == 0:
+            # If logarithmic, default zero to 1
+            self.zero = 1
 
     def __getattr__(self, attr):
         """Search in config, then in self"""
@@ -129,6 +132,7 @@ class BaseGraph(object):
 
     def _draw(self):
         """Draw all the things"""
+        self._prepare_data()
         self._compute()
         self._compute_margin()
         self._decorate()
@@ -142,6 +146,14 @@ class BaseGraph(object):
             return False
         return True
 
+    def _prepare_data(self):
+        """Remove aberrant values"""
+        if self.logarithmic:
+            for serie in self.series:
+                for metadata in serie.metadata:
+                    if metadata.value <= 0:
+                        metadata.value = None
+
     def _uniformize_data(self):
         """Make all series to max len"""
         for serie in self.series:
diff --git a/pygal/graph/graph.py b/pygal/graph/graph.py
index 164542d..3b07461 100644
--- a/pygal/graph/graph.py
+++ b/pygal/graph/graph.py
@@ -55,7 +55,9 @@ class Graph(BaseGraph):
     def _make_graph(self):
         """Init common graph svg structure"""
         self.nodes['graph'] = self.svg.node(
-            class_='graph %s-graph' % self.__class__.__name__.lower())
+            class_='graph %s-graph %s' % (
+                self.__class__.__name__.lower(),
+            'horizontal' if self.horizontal else 'vertical'))
         self.svg.node(self.nodes['graph'], 'rect',
                   class_='background',
                   x=0, y=0,
diff --git a/pygal/serie.py b/pygal/serie.py
index 176b2d3..0e5f36c 100644
--- a/pygal/serie.py
+++ b/pygal/serie.py
@@ -50,7 +50,7 @@ class PositiveValue(Value):
     """Positive or zero value container"""
 
     def __init__(self, value):
-        super(PositiveValue, self).__init__(max(0, value))
+        super(PositiveValue, self).__init__(max(value, 0))
 
 
 class Label(object):
diff --git a/pygal/svg.py b/pygal/svg.py
index 12d15e3..d5b325b 100644
--- a/pygal/svg.py
+++ b/pygal/svg.py
@@ -27,6 +27,7 @@ import os
 import json
 from lxml import etree
 from math import cos, sin, pi
+from urlparse import urlparse
 from pygal.util import template, coord_format
 from pygal import __version__
 
@@ -37,6 +38,8 @@ class Svg(object):
 
     def __init__(self, graph):
         self.graph = graph
+        self.processing_instructions = [
+            etree.PI('xml', "version='1.0' encoding='utf-8'")]
         self.root = None
         self.defs = None
 
@@ -47,24 +50,30 @@ class Svg(object):
             nsmap={
                 None: self.ns,
                 'xlink': 'http://www.w3.org/1999/xlink',
-            },
-            # onload="svg_load(evt);"
-)
+            })
         self.root.append(etree.Comment(
             u'Generated with pygal %s ©Kozea 2012' % __version__))
         self.root.append(etree.Comment(u'http://github.com/Kozea/pygal'))
         self.defs = self.node(tag='defs')
 
-    def add_style(self, css):
+    def add_styles(self):
         """Add the css to the svg"""
-        style = self.node(self.defs, 'style', type='text/css')
-        with io.open(css, encoding='utf-8') as f:
-            templ = template(
-                f.read(),
-                style=self.graph.style,
-                font_sizes=self.graph.font_sizes(),
-                hidden='y' if self.graph.horizontal else 'x')
-            style.text = templ
+        for css in ['base.css'] + list(self.graph.css):
+            if urlparse(css).scheme:
+                self.processing_instructions.append(
+                    etree.PI(
+                        'xml-stylesheet', 'href="%s"' % css))
+            else:
+                if not os.path.exists(css):
+                    css = os.path.join(
+                        os.path.dirname(__file__), 'css', css)
+                with io.open(css, encoding='utf-8') as f:
+                    templ = template(
+                        f.read(),
+                        style=self.graph.style,
+                        font_sizes=self.graph.font_sizes())
+                    self.node(
+                        self.defs, 'style', type='text/css').text = templ
 
     def add_scripts(self):
         """Add the js to the svg"""
@@ -72,13 +81,14 @@ class Svg(object):
         common_script.text = " = ".join(
             ("window.config", json.dumps(self.graph.config.to_dict())))
 
-        for external_js in self.graph.external_js:
-            self.node(
-                self.defs, 'script', type='text/javascript', href=external_js)
-        for included_js in self.graph.included_js:
-            script = self.node(self.defs, 'script', type='text/javascript')
-            with io.open(included_js, encoding='utf-8') as f:
-                script.text = f.read()
+        for js in self.graph.js:
+            if urlparse(js).scheme:
+                self.node(
+                    self.defs, 'script', type='text/javascript', href=js)
+            else:
+                script = self.node(self.defs, 'script', type='text/javascript')
+                with io.open(js, encoding='utf-8') as f:
+                    script.text = f.read()
 
     def node(self, parent=None, tag='g', attrib=None, **extras):
         """Make a new svg node"""
@@ -160,8 +170,7 @@ class Svg(object):
 
     def pre_render(self, no_data=False):
         """Last things to do before rendering"""
-        self.add_style(self.graph.base_css or os.path.join(
-            os.path.dirname(__file__), 'css', 'graph.css'))
+        self.add_styles()
         self.add_scripts()
         self.root.set(
             'viewBox', '0 0 %d %d' % (self.graph.width, self.graph.height))
@@ -179,8 +188,12 @@ class Svg(object):
         """Last thing to do before rendering"""
         svg = etree.tostring(
             self.root, pretty_print=True,
-            xml_declaration=not self.graph.disable_xml_declaration,
+            xml_declaration=False,
             encoding='utf-8')
+        if not self.graph.disable_xml_declaration:
+            svg = '\n'.join(
+                [etree.tostring(pi) for pi in self.processing_instructions]
+            ) + '\n' + svg
         if self.graph.disable_xml_declaration or is_unicode:
             svg = svg.decode('utf-8')
         return svg
diff --git a/pygal/test/__init__.py b/pygal/test/__init__.py
index 98db20d..ac7e4f2 100644
--- a/pygal/test/__init__.py
+++ b/pygal/test/__init__.py
@@ -16,3 +16,34 @@
 #
 # You should have received a copy of the GNU Lesser General Public License
 # along with pygal. If not, see <http://www.gnu.org/licenses/>.
+
+import pygal
+from pygal.util import cut
+
+
+def get_data(i):
+    return [
+        [(-1, 1), (2, 0), (0, 4)],
+        [(0, 1), (None, 2), (3, 2)],
+        [(-3, 3), (1, 3), (1, 1)],
+        [(1, 1), (1, 1), (1, 1)],
+        [(3, 2), (2, 1), (1, 1)]][i]
+
+
+def pytest_generate_tests(metafunc):
+    if "Chart" in metafunc.funcargnames:
+        metafunc.parametrize("Chart", pygal.CHARTS)
+    if "datas" in metafunc.funcargnames:
+        metafunc.parametrize(
+            "datas",
+            [
+                [("Serie %d" % i, get_data(i)) for i in range(s)]
+                for s in (5, 1, 0)
+            ])
+
+
+def make_data(chart, datas):
+    for data in datas:
+        chart.add(data[0],
+                  data[1] if chart.__class__ == pygal.XY else cut(data[1]))
+    return chart
diff --git a/pygal/test/test_config.py b/pygal/test/test_config.py
index daa55c7..ff9e04b 100644
--- a/pygal/test/test_config.py
+++ b/pygal/test/test_config.py
@@ -16,8 +16,9 @@
 #
 # You should have received a copy of the GNU Lesser General Public License
 # along with pygal. If not, see <http://www.gnu.org/licenses/>.
-from pygal import Line
+from pygal import Line, Dot, Pie, Radar
 from pygal.test.utils import texts
+from pygal.test import pytest_generate_tests, make_data
 
 
 def test_logarithmic():
diff --git a/pygal/test/test_graph.py b/pygal/test/test_graph.py
index dc43e02..88309e9 100644
--- a/pygal/test/test_graph.py
+++ b/pygal/test/test_graph.py
@@ -17,38 +17,34 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with pygal. If not, see <http://www.gnu.org/licenses/>.
 import os
-from pygal import Line
 import pygal
 import uuid
+from pygal.util import cut
+from pygal.test import pytest_generate_tests, make_data
 
 
-def test_multi_render():
-    for Chart in pygal.CHARTS:
-        chart = Chart()
-        rng = range(20)
-        if Chart == pygal.XY:
-            rng = zip(rng, rng)
-        chart.add('Serie', rng)
-        chart.add('Serie 2', list(reversed(rng)))
-        svg = chart.render()
-        for i in range(2):
-            assert svg == chart.render()
+def test_multi_render(Chart, datas):
+    chart = Chart()
+    chart = make_data(chart, datas)
+    svg = chart.render()
+    for i in range(2):
+        assert svg == chart.render()
 
 
-def test_render_to_file():
+def test_render_to_file(Chart, datas):
     file_name = '/tmp/test_graph-%s.svg' % uuid.uuid4()
     if os.path.exists(file_name):
         os.remove(file_name)
 
-    line = Line()
-    line.add('Serie 1', [1])
-    line.render_to_file(file_name)
+    chart = Chart()
+    chart = make_data(chart, datas)
+    chart.render_to_file(file_name)
     with open(file_name) as f:
         assert 'pygal' in f.read()
     os.remove(file_name)
 
 
-def test_render_to_png():
+def test_render_to_png(Chart, datas):
     try:
         import cairosvg
     except ImportError:
@@ -58,9 +54,34 @@ def test_render_to_png():
     if os.path.exists(file_name):
         os.remove(file_name)
 
-    line = Line()
-    line.add('Serie 1', [1])
-    line.render_to_png(file_name)
+    chart = Chart()
+    chart = make_data(chart, datas)
+    chart.render_to_png(file_name)
     with open(file_name, 'rb') as f:
         assert f.read()
     os.remove(file_name)
+
+
+def test_metadata(Chart):
+    chart = Chart()
+    v = range(7)
+    if Chart == pygal.XY:
+        v = map(lambda x: (x, x + 1), v)
+
+    chart.add('Serie with metadata', [
+        v[0],
+        {'value': v[1]},
+        {'value': v[2], 'label': 'Three'},
+        {'value': v[3], 'xlink': 'http://4.example.com/'},
+        {'value': v[4], 'xlink': 'http://5.example.com/', 'label': 'Five'},
+        {'value': v[5], 'xlink': {
+            'href': 'http://6.example.com/'}, 'label': 'Six'},
+        {'value': v[6], 'xlink': {
+            'href': 'http://7.example.com/',
+            'target': '_blank'}, 'label': 'Seven'}
+    ])
+    q = chart.render_pyquery()
+    for md in (
+            'Three', 'http://4.example.com/',
+            'Five', 'http://7.example.com/', 'Seven'):
+        assert md in cut(q('desc'), 'text')
diff --git a/pygal/util.py b/pygal/util.py
index 599fe76..5c3cc70 100644
--- a/pygal/util.py
+++ b/pygal/util.py
@@ -123,6 +123,8 @@ ident = lambda x: x
 
 def compute_logarithmic_scale(min_, max_):
     """Compute an optimal scale for logarithmic"""
+    if max_ <= 0 or min_ <= 0:
+        return []
     min_order = int(floor(log10(min_)))
     max_order = int(ceil(log10(max_)))
     positions = []
@@ -199,6 +201,8 @@ def decorate(svg, node, metadata):
     for key in dir(metadata):
         if key not in ('value') and not key.startswith('_'):
             value = getattr(metadata, key)
+            if key == 'xlink' and isinstance(value, dict):
+                value = value.get('href', value)
             if value:
                 svg.node(node, 'desc', class_=key).text = str(value)
     return node