How to make up from the mobile version?

Question

Layout

Hello everyone, this question arose, but how to make up immediately from the mobile version of the site, that is, when the customer writes to you to look at the layouts and estimate the time and cost, and you go to look at the layouts, and there is only a mobile version without a desktop one and he says that first we make a mobile version as they will use it from the phone, and you refuse it, because you don’t know how to make a mobile version right away.

And now the question is how to immediately make sites from the mobile version, that is, first mobile, and then desktop, the reverse layout?

Answer 1

And what's so difficult about immediately imposing a mobile phone. You can still agree with the customer on the minimum and maximum sizes if everything is so complicated)