Additional CSS classes

Hello

I need to add the class “nolightbox” to the posts in my grid.

Neither the advanced option in the layout nor the template actually adds the class, it is nowhere to be seen in the inspector.

I have tried both nolightbox and .nolightbox

Any suggestions as to how I can enforce this class being added would be very useful.

Thank you kindly

ps. Working locally on MAMP so I cannot sen you a link sorry.