Hide a filling table's colgroup on narrow pages instead of !important

CHANGELOG.md

@@ -8,6 +8,14 @@ follows [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## Unreleased
 
+### Fixed
+
+- **A page narrow enough to hide columns gives up their shares without `!important`.** `LayoutCss`
+  hides a filling table's `<colgroup>` there instead of overriding each column's inline width, so a
+  site whose stylesheets forbid `!important` can carry the rule as written.
+
+## 2.11.0 — 2026-10-07
+
 ### Added
 
 - **Tables that fill their width.** `TableColumn.Grow` gives a column a share of the width a table has

MarkupString.Html/LayoutCss.cs

@@ -87,6 +87,6 @@ public static class LayoutCss
 		".ms-table th { border-bottom: 1px solid var(--ms-header-rule, var(--ms-header-rule-default, currentColor)); color: var(--ms-heading, var(--ms-heading-default, inherit)); }\n" +
 		".ms-table.ms-striped > tbody > tr:nth-child(even) { background: var(--ms-stripe, var(--ms-stripe-default, rgba(127, 127, 127, 0.12))); }\n" +
 		".ms-table .ms-nowrap, .ms-table .ms-nowrap .ms-text { white-space: pre; overflow-wrap: normal; }\n" +
-		"@media (max-width: 48em) { .ms-table .ms-p3 { display: none; } .ms-table.ms-fill > colgroup > col { width: auto !important; } }\n" +
+		"@media (max-width: 48em) { .ms-table .ms-p3 { display: none; } .ms-table.ms-fill > colgroup { display: none; } }\n" +
 		"@media (max-width: 32em) { .ms-table .ms-p2 { display: none; } }\n";
 }

MarkupString.Tests/Layout/WidgetLayoutTests.cs

@@ -243,7 +243,7 @@ public async Task Table_InHtml_AGrowingTableFillsThePage()
 		await Assert.That(BlockLayout.Build(Who(), 60).Render(MarkupFormat.Html, Registry)).DoesNotContain("<colgroup>")
 			.Because("a table that does not fill is as wide as its cells");
 		await Assert.That(LayoutCss.Fixed).Contains(".ms-table.ms-fill { width: 100%; }");
-		await Assert.That(LayoutCss.Fixed).Contains(".ms-table.ms-fill > colgroup > col { width: auto !important; }")
+		await Assert.That(LayoutCss.Fixed).Contains(".ms-table.ms-fill > colgroup { display: none; }")
 			.Because("on a page narrow enough to hide columns, their shares are given up");
 	}