# Welcome to the Highcharts Gantt JS (gantt) Options Reference

These pages outline the chart configuration options, and the methods and properties of Highcharts objects.

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# responsive.rules.condition.callback

A callback function to gain complete control on when the responsive rule applies. Return `true` if it applies. This opens for checking against other metrics than the chart size, for example the document size or other elements. Since v12.6.0, the callback also receives `ctx` as the first argument, so that arrow functions can access the same context as regular functions using `this`.