For most businesses, the majority of website traffic now arrives on a phone — but a lot of navigation still gets designed desktop-first and adapted for mobile as an afterthought, which is exactly backwards from how it should be prioritised.
A confusing hamburger menu
If a visitor has to tap the menu icon just to figure out what sections exist at all, that's friction before they've seen anything. The two or three most important links — services, contact, pricing — are often worth surfacing directly instead of hiding everything behind one icon.
Tap targets that are too small
A button sized and spaced for a precise mouse cursor is genuinely hard to tap accurately with a thumb. Mis-taps are a real, measurable source of frustration and abandoned actions on mobile specifically.
A header or footer that eats the whole screen
What looks like a reasonable amount of chrome on a large desktop monitor can dominate a small phone screen, leaving very little actual content visible at once.
Unintended horizontal scrolling
One layout element slightly too wide for the viewport creates a side-scroll that feels broken, even if every other element is fine. It's an easy bug to miss on desktop and immediately obvious on a real phone.
A contact button that's awkward to reach
If the primary conversion action — book, buy, WhatsApp — is genuinely hard to tap reliably on the exact device where most inquiries originate, that's a direct, quantifiable cost, not a minor annoyance.
The fastest real test: borrow an older or budget Android phone, not your own newest one, and try to complete the exact action you want a customer to take, start to finish, with no prior knowledge of the layout.