@urchindesign, no worries! There are basically two “states” to be aware of when you’re working in the tool, both of which are outlined in the Release Notes as mentioned above. Essentially, if you have no responsive breakpoint selected in the Toolbar, it should look something like this:
The circle in the corner of the XS breakpoint represents the “base” value where if you’re not responsive, the core styling is getting applied. The blue highlighted icon in this instance represents the breakpoint you are currently viewing. When you see your Toolbar in this state, you are not styling anything responsively. Anything you change is getting applied to the “base” and applied to all breakpoints. If you were to resize your browser directly in this mode, you would see the blue highlighted icon moving from breakpoint to breakpoint, simply helping you to understand what breakpoint you’re currently seeing, but again, this does not mean you are applying responsive styling.
Once you have selected a responsive breakpoint in the Toolbar, you will see this type of status:
When you see this active state with the blue background and white icon, this means that responsive styling is activated. Only when this state is present, does it mean that you are overwriting something on that breakpoint. So in this example, we can see that the LG breakpoint is selected. This would mean that any changes we make to anything right now will only affect LG and up. If you were to resize your browser around while in this state, you would see this style moving around and it means that responsive styling is still active. So any changes you make on any breakpoint while you see this style means it’s affecting that breakpoint and up. Only once you deselect that toggle to go back to the previous, then you will be back in the “All sizes” mode which is just applying any changes to the base breakpoint.
These two states basically function as the way of knowing whether you’re applying something to “All sizes” or a specific breakpoint on up. Hopefully that helps to provide a little more context on things!