Google PRINCIPLES OF MOBILE SITE DESIGN: DELIGHT USERS AND DRIVE CONVERSIONS - Manual (Page 34)

20. DON’T MAKE USERS
PINCH-TO-ZOOM
Participants were frustrated when they needed to
zoom in or out, and sometimes missed important
messaging and calls-to-action. Design your mobile
site so that users won’t ever need to change the size.
Some mobile sites even disable pinch-to-zoom on
their screens - if your site is designed correctly, users
will never notice it’s gone.
Key Takeaway
Visitors can miss calls-to-action if they
have to zoom in a site. Design your
site so that they never need to.
Example from 1800 Flowers Mobile Site.
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