body {
 background: #FFF2CC; /* color */
}

 simple-theme-plugin:
 elements: |-
 FAILED TO EXPORT
 org.codefirst.SimpleThemeDecorator#elements: io.jenkins.plugins.casc.ConfiguratorException: Can't read attribute 'url' from org.jenkinsci.plugins.simpletheme.CssTextThemeElement@3301b468
 at io.jenkins.plugins.casc.Attribute._getValue(Attribute.java:262)
 at io.jenkins.plugins.casc.Attribute.getValue(Attribute.java:180)
 at io.jenkins.plugins.casc.impl.configurators.DataBoundConfigurator.describe(DataBoundConfigurator.java:250)
 at io.jenkins.plugins.casc.impl.configurators.HeteroDescribableConfigurator.lambda$convertToNode$de0cd4f8$1(HeteroDescribableConfigurator.java:283)
 at io.vavr.CheckedFunction0.lambda$unchecked$52349c75$1(CheckedFunction0.java:201)
 at io.jenkins.plugins.casc.impl.configurators.HeteroDescribableConfigurator.convertToNode(HeteroDescribableConfigurator.java:283)
 at io.jenkins.plugins.casc.impl.configurators.HeteroDescribableConfigurator.lambda$describe$5(HeteroDescribableConfigurator.java:107)
 at io.vavr.control.Option.map(Option.java:373)
 at io.jenkins.plugins.casc.impl.configurators.HeteroDescribableConfigurator.describe(HeteroDescribableConfigurator.java:107)
 at io.jenkins.plugins.casc.impl.configurators.HeteroDescribableConfigurator.describe(HeteroDescribableConfigurator.java:55)
 at io.jenkins.plugins.casc.Attribute.describe(Attribute.java:198)
 at io.jenkins.plugins.casc.Configurator.describe(Configurator.java:161)
 at io.jenkins.plugins.casc.impl.configurators.GlobalConfigurationCategoryConfigurator.describe(GlobalConfigurationCategoryConfigurator.java:106)
 at io.jenkins.plugins.casc.impl.configurators.GlobalConfigurationCategoryConfigurator.lambda$describe$3(GlobalConfigurationCategoryConfigurator.java:99)
 at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:184)
 at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:175)
 at java.util.Iterator.forEachRemaining(Iterator.java:116)
 at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
 at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:482)
 at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:472)
 at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151)
 at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174)
 at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
 at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:418)
 at io.jenkins.plugins.casc.impl.configurators.GlobalConfigurationCategoryConfigurator.describe(GlobalConfigurationCategoryConfigurator.java:99)
 at io.jenkins.plugins.casc.impl.configurators.GlobalConfigurationCategoryConfigurator.describe(GlobalConfigurationCategoryConfigurator.java:30)