Plugins are able to modify rendering of wiki symbols, e.g. tables.

For example, see plugin fitnesse.testsystems.slim.CustomScriptTableRenderingPlugin that has been loaded in SetUp.
This plugin makes an alias from my use case to the existing dummy my fixture. Also, the plugin ensures that all script tables using the new alias will generate an extra class attribute value on the corresponding table HTML tag. This can be then used for custom styling applied via css.

Modify rendering when new alias is used:

script
given page AliasTest with content !define TEST_SYSTEM {slim} |import | |fitnesse.slim.test| |script : my use case | |check|do business logic|42|
check request page AliasTest?test 200
ensure content contains class="pass"
ensure content contains table class="myUseCase"
show content

Do not touch rendering when new alias isn't used:

script
given page AliasTest with content !define TEST_SYSTEM {slim} |import | |fitnesse.slim.test| |script : my fixture | |check|do business logic|42|
check request page AliasTest?test 200
ensure content contains class="pass"
reject content contains table class="myUseCase"
show content