Blog Post

Why Your CSS Never Matches the Figma File

You copied the CSS values exactly. The font-weight, the padding, the hex color. And it still looks wrong. This article covers six root causes: font rendering differences between Figma and browsers, sub-pixel rounding, color space mismatches, nested border-radius math, line-height model differences, and auto layout vs flexbox translation.

Font Rendering: Figma Skia vs Browser Engines

Figma renders text with Skia. Browsers use OS-level engines — Core Text on macOS, DirectWrite on Windows. Same font file, same weight, different rendering. Anti-aliasing, hinting, and -webkit-font-smoothing all contribute to visible differences that persist even when CSS values match the spec exactly.

Sub-Pixel Rounding

Figma allows fractional values like 343.5px or border-width: 0.5px. Browsers round these to device pixels. A 0.5px border becomes 1px. A width of 343.5px rounds to 343px or 344px depending on the engine and context.

Color Space: sRGB vs Display P3

The same hex code renders differently on wide-gamut displays. Figma works in sRGB, but modern displays use Display P3. The CSS color() function and color-gamut media query help bridge the gap.

Nested Border-Radius

Figma smooth corners use a squircle curve, not a CSS arc. And inner border-radius should equal outer radius minus padding — a formula most developers get wrong, creating visible rendering differences.

Line-Height Differences

Figma defines line-height in pixels with a bounding-box model. CSS uses unitless ratios and the half-leading model, distributing extra space above and below the text differently.

Auto Layout vs Flexbox

Figma auto layout maps to CSS flexbox, but the translation is not 1:1. Space-between behavior, hug-contents sizing, and gap calculation all have subtle differences that cause layout drift.

Why Figma Dev Mode Doesn't Catch These Issues

Dev Mode surfaces design specs, CSS values, and component properties inside Figma. But every issue in this article happens after you copy those values — in the browser, during rendering. Dev Mode tells you the font-weight is 600; it does not tell you that 600 renders differently in Chrome on Windows. It gives you border-radius: 16px; it does not calculate that the nested card needs 4px. If you are looking for a Figma Dev Mode alternative that covers the post-build gap, the answer is a verification tool that compares the live build against the design — not a different spec tool.

Frequently Asked Questions

Why does CSS look different from Figma?

Six root causes: font rendering differs between Figma and browsers, sub-pixel values get rounded differently, Figma auto layout and CSS flexbox solve spacing differently, color spaces can shift between sRGB and display-p3, responsive scaling creates gaps between breakpoints, and component states (hover, focus) are static in Figma but dynamic in CSS. These are structural -- they exist in every project.

How do you compare Figma designs to live CSS?

Use a visual comparison tool that compares the Figma frame against the live page in the browser. Adjust opacity to spot misalignments, then click individual elements to compare their computed CSS values against the Figma spec. This is faster and more precise than tab-switching between Figma and the browser.

Can you achieve pixel perfect design from Figma to code?

Yes, with controlled tolerance. Zero deviation is not realistic because browsers render differently than Figma. The practical standard is: spacing and sizing within 1px of spec, exact color match, correct font and weight. A design QA process that compares staging against Figma on every PR achieves this level of fidelity.