As you use the Style panel to design your site, you'll see plain, amber, blue, and pink labels for your properties. Plain label means no change, amber label means this change is being inherited by a combo class or from another breakpoint. Blue label means a change is made on the current breakpoint. Finally, a pink label means a grid child has specific sizing and layout properties.
On pink and blue labels, you can clear or reset those styles by clicking on the label itself, or you can hold down Option or Alt and click on the label.
When a label in the Style panel is amber, by clicking on it, you can see where that style is being inherited from.