mapnik_world.xml

<Map background-color="#a6bddb" srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs">

  <Style name="My Style">
    <Rule>
      <PolygonSymbolizer fill="#e5f5e0" />
      <LineSymbolizer stroke="#31a354" stroke-width="0.2" />
    </Rule>
  </Style>

  <Layer name="world" srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs">
    <StyleName>My Style</StyleName>
    <Datasource>
      <Parameter name="type">shape</Parameter>
      <Parameter name="file">data/world_borders/TM_WORLD_BORDERS-0.3.shp</Parameter>
    </Datasource>
  </Layer>

</Map>