<if_in_folder 123456.0>.......</if_in_folder>

You can change the platform appearance by using this tag. For example, if you open a folder you may want that the left frame color changes or whaterver other stylelistic change happens.

This example shows a style tag, that is originally included in the header of a factline platform. The border color is changing every time a specified folder is opened:

<style>
.platform .leftframe {
    border-right: 8px solid #BABDCD;
<if_in_folder 282194.0>
    border-right: 8px solid #B2B2B2;
</if_in_folder>
<if_in_folder 282203.0>
    border-right: 8px solid #f0e285;
</if_in_folder>
<if_in_folder 282741.0>
    border-right: 8px solid #D7C6D7;
</if_in_folder>
<if_in_folder 282938.0>
    border-right: 8px solid #e7e38c;
</if_in_folder>
}
</style>