default_line.sld

<StyledLayerDescriptor version="1.0.0" xmlns:xsi="http://www.opengis.net/sld http://schemas.opengis.net/sld/1.0.0/StyledLayerDescriptor.xsd">
  <NamedLayer>
    <Name>foo</Name>
    <UserStyle>
      <FeatureTypeStyle>
    <Rule>
      <Name>Class given in default</Name>
      <LineSymbolizer>
        <Stroke>
          <CssParameter name="stroke">#FF7D3F</CssParameter>
          <CssParameter name="stroke-width">1.5</CssParameter>
        </Stroke>
      </LineSymbolizer>
    </Rule>
      </FeatureTypeStyle>
    </UserStyle>
  </NamedLayer>
</StyledLayerDescriptor>