Thank you for contacting Telerik support.
Could you please described what did you mean when you would like to "minimize" the left column? Otherwise, columns in the PageLayout control can be hidden by the properties HiddenSm
Regarding to implement columns of the PageLayout by repeater, we are afraid that it is not possible. You can add another DOM element by a repeater and after that hide or show them by CSS with media queries.
Do not hesitate to contact us if you have other questions.
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