On a phone
Open it on your own phone before anyone else does. Three things give it away.
It is built narrow first
Screens are laid out for a narrow phone and then widened, not the other way round. Done in reverse, phones fall apart.
Across the seven builds we measured, we checked every page at 390 pixels wide. None of them scrolled sideways.
Use it like a customer would
Make a booking on your phone. Put something in the basket. Doing it with a thumb shows you things a mouse never will.
Nothing should run off the side
Swipe left and right on a phone. If the whole page follows your finger, something is sticking out.
Wide tables and large images are the usual causes. Say where you saw it — "the price table runs off the side on my phone" — and it gets fixed.
Input text has to be 16 pixels or more
An iPhone zooms the whole page every time you tap a box whose text is smaller than 16 pixels, and it stays zoomed.
It happened on our own screens, which is why every input here is 16 or above now.
Tap targets are 24 by 24 at minimum
A fingertip is far blunter than a mouse pointer. Small links sit close enough together that the wrong one gets hit.
24 by 24 pixels is the floor. Links sitting inside a sentence are the exception.
Small text is small on a phone
Below 12 pixels, text on a phone is work to read. Prices and opening hours deserve more than the floor.
How to check
The preview address opens on a phone like any other. Open it on yours once the build is done — ten seconds is enough to see all three.