A logo lives in more places than a letterhead. It is a browser tab, a notification badge and a profile picture the size of a thumbnail. If it falls apart there, it falls apart where your customers spend most of their time.
Start small, then scale up
Designing at the smallest size first forces clarity. Remove detail, thicken strokes and make the silhouette recognisable at a glance. A mark that works at 16 pixels will almost always work at 16 feet.
Build a responsive logo system
Most brands need more than one logo file: a full wordmark, a compact lockup and a standalone icon. Define when each is used, and what the minimum size is, so teams never guess.
Test in real contexts
Put the mark in a browser tab, on a phone home screen, in dark mode and in one colour. If it survives all four, it is ready.