CSS and Layout Problems in AI-Generated Front-Ends (and How to Fix Them)

AI assistants are usually better at logic than at layout. The function works and the data is right — but the page is a mess: overlapping boxes, a stray horizontal scrollbar, spacing that's slightly off everywhere you look. Visual problems are the first thing people notice in AI-generated front-ends, partly because they're the easiest to see, and partly because CSS rewards a consistency that generated code doesn't always keep.

Here are the layout problems that come up most, and a plain fix for each.

1. It looks right on one screen and falls apart on phones

The model styled the page for the width it "imagined," often with fixed pixel sizes and no breakpoints. On a phone, columns don't stack and text gets cut off. Fix: swap fixed widths for relative units (%, rem, max-width), let flex or grid items wrap, and add a media query or two. Then actually view it narrow — around 360px wide — before you trust it.

2. A mysterious horizontal scrollbar

Something on the page is wider than the screen: a fixed width, an image with no limit, or an unbroken string of text. Fix: add img { max-width: 100%; }, allow long words to break, and hunt down the too-wide element (temporarily outlining everything with a border makes the offender obvious). A page should never scroll sideways by accident.

3. Overlapping elements and z-index wars

A modal appears behind the page, a sticky header covers the first line of content, a dropdown hides under the next section. Generated code tends to sprinkle z-index numbers that end up fighting each other. Fix: decide on a small, deliberate stacking order (say, content, header, overlays, modals) and use position intentionally rather than adding another z-index: 9999 to win the current battle.

4. Spacing that's inconsistent everywhere

13px here, 17px there, 22px in the next block — magic numbers with no relationship. Nothing is broken, exactly, but it never feels tidy. Fix: pick a spacing scale (4, 8, 12, 16, 24, 32…) and reuse it for margins and padding. Consistent spacing is most of what separates a page that looks designed from one that looks generated.

5. Flexbox and grid that won't line up

Items won't center, or they wrap in a strange way, because the wrong property was applied to the wrong axis. Fix: remember that in a flex row, justify-content controls the horizontal (main) axis and align-items controls the vertical (cross) axis — and they swap when the direction is a column. Naming the axis you actually want fixes most alignment mysteries.

6. Dark mode and contrast as an afterthought

Hardcoded colors look fine in the mode the AI built for and break in the other — light text on a light background, or contrast too low to read. Fix: define colors as variables (tokens) in one place and reference them everywhere, then check that text stays readable in both light and dark, and against its actual background.

7. Copy-pasted styles fighting each other

Each regeneration can leave duplicate or competing rules behind, so two selectors both try to style the same element and the messier one wins. Fix: prune dead styles and consolidate the duplicates. If a change "won't take" no matter what you type, something more specific is overriding it — find that rule rather than piling on !important.

The fastest way to fix layout: see it while you change it

CSS is a visual medium, so the tightest loop is edit-and-look, not prompt-and-wait. Most of the fixes above are one or two properties — a max-width, a flex direction, a spacing value — and you don't need an AI round-trip for any of them. Making small changes by hand is faster than describing them, and it's how you start to actually understand the styles the AI wrote.

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Related: the 15-minute pre-launch review for AI-built sites →