HTML to PDF Browser Parity Coverage
View SourceThis document tracks which documented HTML/CSS/layout features have Chromium visual parity fixtures. A fixture being present means the feature is exercised by the browser-parity harness and must stay within the configured visual-diff threshold.
Run the parity suite with:
CHROMIUM_BIN=/usr/bin/chromium mise exec -- mix test.browser_parity
Current Result
The browser-parity suite contains 35 synthetic HTML fixtures, 5 realistic document fixtures, and guard tests that ensure every fixture has configured thresholds.
Current status: passing. The full suite passes with:
CHROMIUM_BIN=/usr/bin/chromium mise exec -- mix test.browser_parity
New HTML-to-PDF renderer features must add focused unit coverage and, when they affect visible output, a browser parity fixture or an update to an existing fixture. Do not mark new HTML/CSS/layout behavior as supported until the relevant unit tests and browser parity suite pass.
Fixture Catalog
| Fixture | Coverage |
|---|---|
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, hidden elements, unordered lists, ordered lists, list item spacing |
fonts_and_print_media.html | local CSS @font-face, 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 |
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 documents currently used in real production environments and use the same print sizes as those production render calls.
| 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 |
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 |
Current production fixture parity:
| Fixture | Current signal |
|---|---|
government_application_form.html | Passing current parity thresholds. |
purchase_order.html | Passing current parity thresholds. |
material_requisition.html | Passing current parity thresholds. |
trim_card.html | Passing current parity thresholds. |
stock_sticker.html | Passing current parity 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: 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, background, overflow, position | Passing | block_box_model.html, box_sizing_and_margins.html, css_remaining_supported_values.html, table_column_layout.html, table fixtures |
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 |
| 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/layout support area now has at least one Chromium parity fixture, and the current suite passes. The suite is still not a claim of full browser compatibility; it is a release checklist for the documented renderer surface. When expanding that surface, update this coverage map, add or update fixtures, and keep mix test.browser_parity green.