Supported CSS in mPDF

Written for mPDF 8.2 on PHP 8.1+. Updated 2 November 2026.

mPDF implements a solid part of CSS 2.1, some CSS 3 and the paged-media rules print needs. It does not try to match a modern browser. Knowing where the line is saves hours.

Works well

Text: font-family, font-size, font-weight, font-style, color, line-height, letter-spacing, word-spacing, text-align (including justify), text-indent, text-transform, text-decoration, text-shadow.
Box model: margin, padding, border (all styles), border-radius, width, height, box-shadow on block elements.
Colour: names, hex, rgb(), rgba(), CMYK with cmyk(), and opacity.
Backgrounds: colours, images, linear-gradient() and radial-gradient() (see backgrounds and borders).
Paged media: @page with size, margins, headers and footers, plus named pages, page-break-before, page-break-after and, on tables, page-break-inside: avoid.
Positioning: float on block elements, and position: absolute or fixed for blocks placed relative to the page, which suits letterheads and stamps.
Selectors: element, class, id and descendant selectors, plus :first-child and :nth-child(odd|even) on table rows.

Not supported, and what to do instead

Not supported	Instead
`display: flex` and `grid`	A table with fixed column widths, or floated blocks with set widths.
`display: inline-block`	A table cell, or a float.
CSS custom properties (`var(--x)`)	Generate the values in PHP, or run a preprocessor first.
`@font-face`	Register the font in the `fontdata` config (how).
`calc()`, `vw`/`vh` units	Fixed sizes in mm, pt or %.
Complex selectors (`~`, `+`, most pseudo-classes)	Add a class to the element.
`transform` on ordinary blocks	`rotate` on tables, or images rotated beforehand.

Units

On paper, use mm or pt. Pixels are converted at the dpi setting (96 by default), which is fine for borders but unpredictable for page-sized boxes. Percentages work against the containing block.

A quick test

When a style doesn’t apply, isolate it in a ten-line document. If it fails there too, it isn’t supported, and a table-based layout is usually the fastest way around it. The examples gallery shows layouts that render the same in mPDF and in browsers.