diff --git a/tests/test_site_r3_css.py b/tests/test_site_r3_css.py
new file mode 100644
index 00000000..b78dde38
--- /dev/null
+++ b/tests/test_site_r3_css.py
@@ -0,0 +1,94 @@
+"""Round 3 theme: the stylesheet fixes of package 1, read from its source.
+
+Each test fails on the stylesheet as it was before the fix: commands allowed
+to break inside any word on a phone, a sidebar whose top links outsize its
+group labels, OS tabs on two rows, badge links cut to a few pixels by the
+next row, 12 px hashes, Get your files tables each sizing their own columns.
+"""
+from __future__ import annotations
+
+import unittest
+
+from tests.test_site_r2_css import CSS_PATH, PAGE_BG, _blocks, _ratio, _rules, _strip_comments, _theme_tokens
+
+PACKS = "table.rb-packs"
+
+
+class ThemeStylesheetRound3(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls) -> None:
+        cls.css = _strip_comments(CSS_PATH.read_text(encoding="utf-8"))
+        dark = _theme_tokens(cls.css, ":root")
+        light = {**dark, **_theme_tokens(cls.css, ":root[data-theme='light']")}
+        cls.tokens = {"dark": dark, "light": light}
+
+    # 1.1
+    def test_commands_never_break_inside_a_word(self):
+        blocks = _rules(self.css, ".expressive-code pre > code")
+        self.assertTrue(blocks)
+        for body in blocks:
+            self.assertIn("white-space: pre-wrap", body, "commands keep wrapping")
+            self.assertNotIn("overflow-wrap: anywhere", body)
+        for selector in (".rb-facts code", ".rb-hash code", ".rb-meta-card td code"):
+            with self.subTest(selector=selector):
+                self.assertIn("overflow-wrap: anywhere", _rules(self.css, selector)[0])
+
+    # 1.2
+    def test_sidebar_labels_above_links(self):
+        label = _rules(self.css, ".top-level summary .large")[0]
+        # 13 px grey semibold, no uppercase: the house style refuses small caps.
+        for declaration in ("font-size: var(--sl-text-xs)", "font-weight: 600", "color: var(--rb-text-secondary)"):
+            with self.subTest(declaration=declaration):
+                self.assertIn(declaration, label)
+        links = next(b for s, b in _blocks(self.css) if s == "#starlight__sidebar .top-level a")
+        self.assertIn("font-size: var(--sl-text-sm)", links)
+        self.assertIn("font-weight: 400", links)
+
+    # 1.3
+    def test_os_tabs_on_one_row(self):
+        tablist = next(b for s, b in _blocks(self.css) if s == "starlight-tabs [role='tablist']")
+        self.assertIn("flex-wrap: nowrap", tablist)
+        self.assertIn("overflow-x: auto", tablist)
+        self.assertIn("scrollbar-width: none", tablist)
+        self.assertIn("display: none", _rules(self.css, "starlight-tabs [role='tablist']::-webkit-scrollbar")[0])
+
+    # 1.4
+    def test_badge_links_keep_a_24px_target(self):
+        dd = next(b for s, b in _blocks(self.css) if s == ".sl-markdown-content .rb-facts dd")
+        self.assertIn("line-height: 1.8", dd)
+        badge = _rules(self.css, ".rb-facts :is(.rb-badge:has(> a), a.rb-badge)")[0]
+        for declaration in ("display: inline-flex", "align-items: center", "min-height: 24px", "margin-block: 2px"):
+            with self.subTest(declaration=declaration):
+                self.assertIn(declaration, badge)
+
+    # 1.5
+    def test_hashes_are_13px_at_every_width(self):
+        hashes = [b for s, b in _blocks(self.css) if ".rb-hash" in s and "font-size" in b]
+        self.assertEqual(len(hashes), 1, "a second size for .rb-hash, on phones")
+        self.assertIn("font-size: 0.8125rem", hashes[0])
+        short = _rules(self.css, "td code[title]")[0]
+        self.assertIn("white-space: nowrap", short)
+        self.assertIn("underline dotted", short)
+        self.assertIn("min-width: 12rem", _rules(self.css, "td.rb-reason")[0])
+
+    # 1.6
+    def test_pack_tables_share_their_columns(self):
+        base = next(b for s, b in _blocks(self.css) if PACKS in s and "table-layout" in b)
+        self.assertIn("table-layout: fixed", base)
+        self.assertIn("width: 100%", base)
+        widths = {s.rsplit("th:nth-child(", 1)[1].split(")")[0]: b for s, b in _blocks(self.css)
+                  if PACKS in s and "th:nth-child(" in s}
+        self.assertEqual({k: v.strip() for k, v in widths.items()},
+                         {"1": "width: 18%;", "2": "width: 20%;", "3": "width: 40%;", "4": "width: 22%;"})
+        parts = next(b for s, b in _blocks(self.css) if PACKS in s and s.endswith(":is(a, .rb-button)"))
+        self.assertIn("white-space: nowrap", parts)
+
+    def test_secondary_text_on_the_sidebar_meets_aa(self):
+        for theme in ("light", "dark"):
+            with self.subTest(theme=theme):
+                fg = self.tokens[theme]["--rb-text-secondary"].strip()
+                self.assertGreaterEqual(_ratio(fg, PAGE_BG[theme]), 4.5)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/wiki/testing-guide.md b/wiki/testing-guide.md
index e4deae8a..a470adaa 100644
--- a/wiki/testing-guide.md
+++ b/wiki/testing-guide.md
@@ -54,7 +54,7 @@ Every module in `tests/`, by the area it guards.
 | Installer and downloads | loopback server | `test_check_release`, `test_download`, `test_install`, `test_install_cores`, `test_install_experience`, `test_install_offline`, `test_install_selection` |
 | Handheld port | stubbed PortMaster dialogs, fake installer | `test_port` |
 | Truth and native export | synthetic + cached originals | `test_export_counts`, `test_export_native_layer`, `test_export_report`, `test_exporters`, `test_truth_data_dir_readers`, `test_truth_diff`, `test_truth_layout` |
-| Scrapers, upstream and provenance | inline sources, synthetic | `test_batocera_md5_list`, `test_check_freshness`, `test_contributing_text`, `test_coverage_cache`, `test_data_dir_refs`, `test_dataclass_defaults`, `test_dedup`, `test_doc_pages`, `test_doc_surfaces`, `test_elec_scrapers`, `test_fbneo_parser`, `test_find_pinned_revision`, `test_hash_merge`, `test_launchers`, `test_launchers_emudeck`, `test_launchers_recalbox`, `test_launchers_retrobat`, `test_launchers_retrodeck`, `test_launchers_retropie`, `test_launchers_rocknix`, `test_mame_devices`, `test_mame_parser`, `test_mame_ref_audit`, `test_optional_dependencies`, `test_profile_sync`, `test_prose_style`, `test_provenance`, `test_refresh_data_dirs`, `test_refresh_failures`, `test_refresh_stale`, `test_retrodeck_scraper_errors`, `test_romset_recipes`, `test_schema_semantic_gate`, `test_scraper_contract`, `test_site_availability`, `test_site_content_data`, `test_site_copy`, `test_site_cores`, `test_site_emulator_page`, `test_site_exports`, `test_site_funnel`, `test_site_images`, `test_site_picker`, `test_site_platform_hashes`, `test_site_r2_components`, `test_site_r2_css`, `test_site_r2_emulators`, `test_site_r2_entry`, `test_site_r2_gate`, `test_site_r2_nav`, `test_site_r2_p0`, `test_site_r2_reference`, `test_site_r2_systems`, `test_site_r2_wiki`, `test_site_r3_p0`, `test_site_render`, `test_site_system_links`, `test_site_validation`, `test_site_weight`, `test_site_write`, `test_upstream`, `test_upstream_index`, `test_validate_pr`, `test_validate_pr_flow`, `test_validate_pr_hashes`, `test_workflow_paths` |
+| Scrapers, upstream and provenance | inline sources, synthetic | `test_batocera_md5_list`, `test_check_freshness`, `test_contributing_text`, `test_coverage_cache`, `test_data_dir_refs`, `test_dataclass_defaults`, `test_dedup`, `test_doc_pages`, `test_doc_surfaces`, `test_elec_scrapers`, `test_fbneo_parser`, `test_find_pinned_revision`, `test_hash_merge`, `test_launchers`, `test_launchers_emudeck`, `test_launchers_recalbox`, `test_launchers_retrobat`, `test_launchers_retrodeck`, `test_launchers_retropie`, `test_launchers_rocknix`, `test_mame_devices`, `test_mame_parser`, `test_mame_ref_audit`, `test_optional_dependencies`, `test_profile_sync`, `test_prose_style`, `test_provenance`, `test_refresh_data_dirs`, `test_refresh_failures`, `test_refresh_stale`, `test_retrodeck_scraper_errors`, `test_romset_recipes`, `test_schema_semantic_gate`, `test_scraper_contract`, `test_site_availability`, `test_site_content_data`, `test_site_copy`, `test_site_cores`, `test_site_emulator_page`, `test_site_exports`, `test_site_funnel`, `test_site_images`, `test_site_picker`, `test_site_platform_hashes`, `test_site_r2_components`, `test_site_r2_css`, `test_site_r2_emulators`, `test_site_r2_entry`, `test_site_r2_gate`, `test_site_r2_nav`, `test_site_r2_p0`, `test_site_r2_reference`, `test_site_r2_systems`, `test_site_r2_wiki`, `test_site_r3_css`, `test_site_r3_p0`, `test_site_render`, `test_site_system_links`, `test_site_validation`, `test_site_weight`, `test_site_write`, `test_upstream`, `test_upstream_index`, `test_validate_pr`, `test_validate_pr_flow`, `test_validate_pr_hashes`, `test_workflow_paths` |
 
 ## Test architecture