Small screens are not a compressed desktop. The user holds the device in one hand, often while walking, in daylight, on a network that may drop. Every design decision that ignores that context turns into a mistap or an abandoned session. The useful question is not how to fit the desktop layout into 390 pixels, but what the person came to do and what can wait.
Write down what the visitor must see first and what can sit lower. On a phone anything that does not earn its place should be removed rather than shrunk. Put the primary action high, keep supporting detail below, and drop the sections that exist only because a competitor has them. At Q8DM every mobile project starts with that list before a design file is opened. One clear path beats four half-visible options.
Most use is one-handed, and the thumb naturally covers the lower and middle area of the screen. Place frequent actions there, and keep destructive ones away from the edges where a grip can trigger them. Aim for touch areas around 44 to 48 pixels and leave at least 8 pixels between separate targets.
A long form on a phone kills completion. Split it into short steps, ask only for what the task requires, and match the keyboard to the field type. Tables are harder still: horizontal scrolling is technically possible and practically unusable. Turn each row into a card with the three values that matter, or show two columns and reveal the rest on tap.
An empty screen is a chance to guide, not a dead end. Say why it is empty and offer one obvious next step. Errors should name the field and explain the fix in plain language, because a generic banner above the form forces the user to re-read everything. Validate inline, under the input, before submission rather than after.
Open the product on a real phone on a weak connection, not a desktop window resized to phone width. Walk the full path standing up, with one hand, in daylight if you can. Note where people stall and where they tap the wrong thing. The recurring mistakes are familiar: text below 16 pixels, cramped tap targets, full-screen popups that hide the content, and close buttons too small to hit.
Q8DM has worked on small-screen UX since 1998, and the pattern holds: a handful of small fixes usually beats a full redesign. If you want your mobile journey reviewed, start at q8dm.com.