| <!DOCTYPE html> |
| <meta charset="utf-8"> |
| <link rel="author" href="mailto:[email protected]"> |
| <link rel="help" href="https://www.w3.org/TR/css-position-3/#fixed-cb"> |
| <link rel="help" href="https://github.com/w3c/csswg-drafts/issues/12352"> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <style> |
| #a, #b, #c, #d, #e, #f { |
| position: fixed; |
| } |
| #margin { |
| margin: 10px; |
| } |
| #transform { |
| transform: translateX(10px); |
| } |
| #perspective { |
| perspective: 10px; |
| } |
| #filter { |
| filter: opacity(25%); |
| } |
| #contain { |
| contain: paint; |
| } |
| </style> |
| |
| <body> |
| <div id="a"></div> |
| <div id="margin"> |
| <div><div id="b"></div></div> |
| </div> |
| |
| <div id="transform"> |
| <div><div id="c"></div></div> |
| </div> |
| <div id="perspective"> |
| <div><div id="d"></div></div> |
| </div> |
| <div id="filter"> |
| <div><div id="e"></div></div> |
| </div> |
| <div id="contain"> |
| <div><div id="f"></div></div> |
| </div> |
| </body> |
| |
| <script> |
| test(() => { |
| assert_equals(a.offsetParent, null); |
| assert_equals(b.offsetParent, null); |
| }, 'If the containing block for a fixed positioned element is viewport, the offsetParent should be null.'); |
| |
| test(() => { |
| assert_equals(c.offsetParent, transform); |
| assert_equals(d.offsetParent, perspective); |
| assert_equals(e.offsetParent, filter); |
| assert_equals(f.offsetParent, contain); |
| }, 'If the containing block for a fixed positioned element is the nearest ancestor box, the offsetParent should be the nearest ancestor box.'); |
| </script> |
