[edit] Update Grid first paragraph to: Most Firefox for desktop icons live on a 16×16 pixel grid. Some specific small icons, used in rare cases, live on a 12×12 pixel grid. Keep icon shape weighted towards the middle area of the grid, reserving the outer 1px margin for visual weighting and maintaining relative aspect ratios. Designing with the pixel grid on helps ensure that icons will not appear fuzzy in production.
[edit] Update Grid first paragraph to: Most Firefox for desktop icons live on a 16×16 pixel grid. Some specific small icons, used in rare cases, live on a 12×12 pixel grid. Keep icon shape weighted towards the middle area of the grid, reserving the outer 1px margin for visual weighting and maintaining relative aspect ratios. Designing with the pixel grid on helps ensure that icons will not appear fuzzy in production.

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