A static mockup is a promise about how a page will feel, and it is usually a lie. Two screens that look identical can feel completely different once they start to move.
Mockups hide the hard questions
What happens between two states? How long does a card take to open? Where does your eye go while the page loads? None of this exists in a flat file, so it gets decided at the last minute by whoever builds the site.
Prototype the feeling first
We now start every project with a rough motion prototype: grey boxes, real timing, real scroll. Once the rhythm feels right, the visual design has something solid to sit on.
Prototype the scroll before the screens
Test on the slowest phone in the office
Agree on easing curves the way you agree on colours
It feels slower in week one and saves weeks of revisions later.
