Consistent sizing.
WHAT A TYPE SCALE IS
A defined set of sizes used throughout, rather than arbitrary values.
WHY
Arbitrary sizes produce subtle inconsistency and endless decisions.
HOW MANY SIZES
Few. Five or six covers most interfaces.
WHAT TO DEFINE
A body size, as the anchor Sizes above it for headings A size or two below for secondary text
WHAT TO ENSURE
Adjacent sizes are distinguishable.
Two sizes that look almost the same serve no purpose.
WHAT ELSE TO DEFINE
Weight for each role Line spacing for each size
WHY LINE SPACING VARIES
Larger text needs proportionally less.
WHAT TO NAME THEM BY
Their role, not their size.
Why: the size can change without renaming everything.
WHAT TO DOCUMENT
Which size is used for what.
WHAT TO ENFORCE
That new work uses the scale.
WHAT HAPPENS OTHERWISE
Sizes proliferate and consistency disappears within months.
