[css-forms-1] Add checkmark content for indeterminate checkboxes (w3c#13358)

lukewarlow · web-flow · commit cf11ed5770e8 · 2026-03-05T18:20:29.000Z
diff --git a/css-forms-1/Overview.bs b/css-forms-1/Overview.bs
@@ -894,11 +894,15 @@ input[type=radio]::checkmark {
     content: '';
 }
 
-input[type=checkbox]:not([switch], :checked)::checkmark {
+input[type=checkbox]:not([switch], :checked, :indeterminate)::checkmark {
 input[type=radio]:not(:checked)::checkmark {
     visibility: hidden;
 }
 
+input[type=checkbox]:indeterminate::checkmark {
+    content: '\2500' / '';
+}
+
 input[type=radio] {
     border-radius: 50%;
 }

Original file line number	Diff line number	Diff line change
`@@ -894,11 +894,15 @@ input[type=radio]::checkmark {`
`894`	`894`	`content: '';`
`895`	`895`	`}`
`896`	`896`
`897`		`-input[type=checkbox]:not([switch], :checked)::checkmark {`
	`897`	`+input[type=checkbox]:not([switch], :checked, :indeterminate)::checkmark {`
`898`	`898`	`input[type=radio]:not(:checked)::checkmark {`
`899`	`899`	`visibility: hidden;`
`900`	`900`	`}`
`901`	`901`
	`902`	`+input[type=checkbox]:indeterminate::checkmark {`
	`903`	`+ content: '\2500' / '';`
	`904`	`+}`
	`905`	`+`
`902`	`906`	`input[type=radio] {`
`903`	`907`	`border-radius: 50%;`
`904`	`908`	`}`