A studio sent iPhone screenshots of their published guideline, and three parts broke on the narrow screen: the clear-space caption ran into the logo, the colour band turned vertical and the typography columns squeezed down to one letter per line.
All three are fixed. On a phone the clear-space caption moves under its diagram and the long note hides, the colour band stays a horizontal strip with a legend you can tap underneath, and the Columns layout stacks its typefaces. A new Show percentages switch in the Color section hides the numbers on the band if you'd rather not show them.
Checking the live guidelines on a phone turned up one more: in the default typography layout the weight comparison collided, so phones now get one cell per weight. All of this is about how pages draw, so every published guideline has it already and there's nothing you need to do.