HTML to PDF browser parity coverage
View SourceThis catalog maps documented HTML, CSS, and layout behavior to Chromium comparison fixtures. Each listed fixture must remain within its configured pixel-difference thresholds.
Run the parity suite with:
CHROMIUM_BIN=/usr/bin/chromium mise exec -- mix test.browser_parity
Current result
The suite contains 38 synthetic HTML fixtures and 8 production document fixtures. Guard tests require thresholds for every fixture. Most fixtures allow at most 5% changed pixels. The geometric absolute-positioning fixture allows 1%, and the trim-card fixture allows 5.5% because of subpixel text and border rasterization. Every average channel-delta limit is 5% or lower.
Current status: passing.
New renderer behavior needs focused unit tests. If it changes visible output, add or update a parity fixture before documenting support.
Fixture catalog
| Fixture | Coverage |
|---|---|
absolute_positioning.html | relative containing blocks, absolute offsets, percentages, nested positioning, negative and positive z-index, and removal from normal flow |
background_images.html | data URI background images, repeat and no-repeat painting, explicit and zero-sized tiles, cover, positioned backgrounds, and shorthand resets of earlier image state |
block_box_model.html | margin, padding, width, min-height, side-specific borders, background, border radius, text alignment |
border_style_variants.html | all ten standard border styles, one-to-four-value side styles and colors, and transparent borders |
box_sizing_and_margins.html | box-sizing, min/max width, percentage width, negative margins, clamped block sizing |
break_variants.html | break-before, break-after, page-break-before, page-break-inside, auto and forced break values |
css_cascade_selectors.html | universal, element, class, id, child, descendant, :first-child, :last-child, :nth-child, !important, forward-referenced custom properties, display: none |
generated_content_counters.html | attribute selectors, :not(), odd/even and type-position selectors, ::before, ::after, attr(), named counter reset/increment/output |
css_remaining_supported_values.html | grouped selectors, source order, inline style priority, inheritance, inline flex/grid, min(), named colors, no-op overflow/position, side padding/borders, vertical-align, line-break, word-wrap |
display_lists_and_inline_block.html | inline-block layout with inline and block contents, mixed inline/block flow, hidden elements, unordered lists, ordered lists, list item spacing |
fonts_and_print_media.html | ordered local CSS @font-face source fallback, print-only media cascade, embedded font output, bundled Unicode glyph fallback from a built-in font |
flex_direction_and_justification.html | flex row, row-reverse, column, grow/shrink/basis, main-axis min/max freezing and redistribution, justify-content, align-items, align-self, row gaps |
flex_grid_alignment.html | flex order, wrapping, gap, alignment, grid template tracks, grid spans, row/column gaps |
grid_tracks_and_placement.html | repeat(), minmax() growth and minimum-bound overflow, auto rows/columns, grid-column, grid-row, grid-area, item alignment |
html_semantics_typography.html | semantic block aliases, metadata wrappers, title, lang, h1-h6, b, i, font-relative semantic margins |
images_data_uris.html | 8-bit non-interlaced RGB PNG, JPEG, and SVG data URI images in block, table, flex, and grid contexts |
image_object_fitting.html | replaced-image sizing, object-fit: contain/cover, percentage object positions, clipping, and image borders |
inline_text_flow.html | inline runs, bold, italic, colors, line-height, wrapping, <br>, text transform |
layout_compositions_remaining.html | grid containing table, flex containing table, table containing direct flexbox |
links_entities_and_protocols.html | links, https, http, mailto, named entities, decimal and hex numeric entities, non-breaking-space wrapping |
static_form_controls.html | static text inputs, checked and unchecked checkbox/radio state, selected options, multiline textarea content, buttons, Boolean attributes, and CSS-targeted disabled appearance |
nested_table_collapsed_borders.html | collapsed outer table containing a collapsed inner table, nested colspan, side-specific nested borders, and nested background/border paint order |
nested_table_grid_flex.html | table cell containing grid, grid item containing flexbox, ordering, gaps, nested borders |
page_geometry_asymmetric.html | named page sizing, landscape orientation, and asymmetric one-to-four-value @page margins |
page_rules_landscape.html | CSS @page landscape sizing, page margins, explicit page-sized drawing geometry |
page_furniture.html | repeated header and footer placement inside page margins across multiple pages, including visible current-page and total-page tokens |
paragraph_pagination.html | default line-level paragraph fragmentation across automatic page breaks |
pagination_breaks.html | explicit page breaks, repeated page-sized sections, page count parity |
table_collapsed_borders.html | table captions, headers, collapsed borders, side-specific border precedence, colspan, missing trailing cells |
table_column_layout.html | colgroup, col, column span, percentage column widths, lone cells remaining in their first declared column, table-layout: fixed, and separate/collapsed border-spacing behavior |
table_header_near_page_row.html | a repeated table header kept with the first body row when both fit on a fresh page |
table_pagination_headers.html | table overflow pagination, repeated multi-row header expectations, page breaks around table rows |
table_rowspan_tfoot.html | rowspan, tfoot, vertical alignment, footer rows, colspan totals |
table_separate_borders.html | separate borders, captions, headers, cell padding, colspan, right-aligned table content |
text_style_variants.html | rgb(), rgba() text and backgrounds, transparent text and borders, currentColor, nested custom properties, inherited unitless line height, white-space, word breaking, letter spacing, text transforms |
unsupported_glyph_replacement.html | browser-compatible continuation for unsupported text, including C1 controls and private-use glyphs, with deterministic U+FFFD replacement in native output |
units_and_sizing.html | pt, px, mm, cm, in, root-font-relative rem, percentages, aspect-ratio, fixed height, min-height |
whitespace_pre_line.html | default whitespace collapse, white-space: pre-line, <br>, literal escaped newline text, centered and right-aligned lines |
Production fixture catalog
These fixtures mirror production documents and use their production print sizes.
| Fixture | Production document type | Browser parity setting |
|---|---|---|
government_application_form.html | Government-style permit application with static form controls | A4 document size |
purchase_order.html | Purchase order printout | A4 production document size |
material_requisition.html | Material requisition printout | A4 production document size |
invoice_012.html | Production-style invoice | A4 production document size |
statement_012.html | Production-style account statement | A4 production document size |
multi_page_report_012.html | Production-style multi-page report | A4 production document size |
stock_sticker.html | Stock sticker label | {4.92126, 1.49606} production label size |
trim_card.html | Trim card printout using the production table, column-group, full-height nested-table, and sheet-break structure | {11.6929, 8.2677} production landscape document size |
All eight production fixtures currently pass their thresholds.
HTML coverage
| Feature | Status | Fixtures |
|---|---|---|
doctype, html, head, body, style, meta, title | Passing | All fixtures, html_semantics_typography.html |
Block tags: article, aside, div, footer, header, main, nav, section, p | Passing | html_semantics_typography.html, suite-wide block fixtures |
Headings h1 through h6 | Passing | html_semantics_typography.html |
Inline tags: span, strong, b, em, i, a, br | Passing | inline_text_flow.html, html_semantics_typography.html, links_entities_and_protocols.html |
| HTML entities | Passing | links_entities_and_protocols.html |
Lists: ul, ol, li | Passing | display_lists_and_inline_block.html |
Tables: table, caption, colgroup, col, thead, tbody, tfoot, tr, th, td | Passing | Table fixtures, especially table_column_layout.html and table_rowspan_tfoot.html |
| Images: 8-bit non-interlaced RGB/RGBA PNG, JPEG, SVG data URIs | Passing | images_data_uris.html |
| Static controls: text input, checkbox, radio, select/option, textarea, button | Passing | static_form_controls.html, government_application_form.html |
Attributes: id, class, style, title, role, data-*, aria-*, lang, metadata attributes, href, src, alt, form type/value/name/checked/selected/disabled, column span, cell colspan/rowspan, and header scope | Passing | generated_content_counters.html, css_cascade_selectors.html, html_semantics_typography.html, links_entities_and_protocols.html, images_data_uris.html, static_form_controls.html, table fixtures |
Link protocols: https, http, mailto | Passing | links_entities_and_protocols.html |
CSS coverage
| Feature | Status | Fixtures |
|---|---|---|
Selectors: universal, element, class, id, element/class, attribute presence/equality, descendant, direct child, comma groups, :not(), :root, child position, type position, ::before, ::after | Passing | generated_content_counters.html, css_cascade_selectors.html, css_remaining_supported_values.html |
Generated content and counters: quoted content, attr(), counter(), reset, increment | Passing | generated_content_counters.html |
Cascade: specificity, source order, inline style priority, !important, inheritance, recursively resolved custom properties via var() | Passing | css_cascade_selectors.html, css_remaining_supported_values.html, text_style_variants.html |
Units: pt, px, root-font-relative rem, mm, cm, in, percentages, unitless 0 | Passing | units_and_sizing.html, reset rules across fixtures |
Display: block, inline, inline-block, none, flex, inline-flex, grid, inline-grid | Passing | display_lists_and_inline_block.html, css_remaining_supported_values.html, flex/grid fixtures |
Box model and painting: width/height, min/max width/height, min(), aspect-ratio, box-sizing, margin, negative margin, padding, side-specific padding, borders, border radius, border collapse, border spacing, table layout, backgrounds, background images, and overflow | Passing | block_box_model.html, box_sizing_and_margins.html, background_images.html, css_remaining_supported_values.html, table_column_layout.html, table fixtures |
Positioning: static, relative and absolute boxes, inset offsets, containing blocks, and z-index paint ordering | Passing | absolute_positioning.html |
Text: color, font family/size/weight/style, relative and absolute line-height inheritance, left/center/right alignment, transform, vertical align, line breaking, word breaking, default and pre-line whitespace, letter spacing | Passing | whitespace_pre_line.html, inline_text_flow.html, text_style_variants.html, css_remaining_supported_values.html, table fixtures |
Colors: hex, named colors, rgb(), rgba(), currentColor, transparent | Passing | text_style_variants.html, css_remaining_supported_values.html |
Page rules and breaks: @page, @media print, break-before, break-after, page-break-before, page-break-after, page-break-inside | Passing | page_geometry_asymmetric.html, page_rules_landscape.html, fonts_and_print_media.html, pagination_breaks.html, break_variants.html |
Flexbox subset: direction, wrap, gap, row/column gap, justify/align, order, grow/shrink/basis, main-axis min/max freezing and redistribution, flex, inline flex | Passing | flex_direction_and_justification.html, flex_grid_alignment.html, css_remaining_supported_values.html |
Grid subset: template rows/columns, auto rows/columns, repeat(), minmax() growth and minimum-bound overflow, placement, area, gaps, justify/align items/content/self, inline grid | Passing | grid_tracks_and_placement.html, flex_grid_alignment.html, css_remaining_supported_values.html |
Layout interaction coverage
| Interaction | Status | Fixtures |
|---|---|---|
| Block flow with nested inline text | Passing | inline_text_flow.html, block_box_model.html |
| Lists in normal flow | Passing | display_lists_and_inline_block.html |
| Table with collapsed borders | Passing | table_collapsed_borders.html |
| Table with separate borders | Passing | table_separate_borders.html |
| Table column groups, fixed layout, border spacing, explicit table heights, and percentage-height nested tables | Passing | table_column_layout.html, trim_card.html |
Table with colspan, rowspan, tfoot, and missing trailing cells | Passing | table_collapsed_borders.html, table_rowspan_tfoot.html |
| Table repeated headers and table pagination | Passing | table_pagination_headers.html |
| Nested table inside collapsed table | Passing | nested_table_collapsed_borders.html |
| Table cell containing grid containing flex | Passing | nested_table_grid_flex.html |
| Grid containing table, flex containing table, table containing direct flex | Passing | layout_compositions_remaining.html |
| Page breaks around complete blocks, including backgrounds and nested children | Passing | pagination_breaks.html, break_variants.html, trim_card.html |
| Page breaks inside/around tables | Passing | table_pagination_headers.html |
| Running headers, footers, and current/total page-number tokens inside page margins | Passing | page_furniture.html |
| Images inside block/table/flex/grid | Passing | images_data_uris.html |
Replaced-image contain and cover fitting with clipping and object positioning | Passing | image_object_fitting.html |
| Repeated and fitted background images inside bordered boxes | Passing | background_images.html |
| Absolute descendants inside relative containing blocks with ordered painting | Passing | absolute_positioning.html |
| Embedded/system font metrics, Unicode fallback, and unsupported glyph replacement vs Chromium | Passing | fonts_and_print_media.html exercises both declared DejaVu Sans and built-in Helvetica text that falls back to bundled DejaVu glyphs; unsupported_glyph_replacement.html exercises visible continuation for unsupported graphemes; production fixtures use their declared font families when registered by the test helper |
Summary
Every documented HTML, CSS, and layout area has at least one Chromium fixture,
and the suite currently passes. This does not establish full browser
compatibility. It checks the behavior this renderer documents. When adding
supported behavior, update this catalog and its fixtures, then run
mix test.browser_parity.