| <!doctype html> |
| <html> |
| <head> |
| <link rel="help" href="https://www.w3.org/TR/css-position-3/#def-cb"> |
| <link rel="help" href="https://crbug.com/970171"> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <style> |
| #container { |
| position: relative; |
| border: 1px solid black; |
| } |
| .narrow { |
| width: 200px; |
| height: 300px; |
| } |
| .wide { |
| width: 300px; |
| height: 200px; |
| } |
| #target { |
| background: green; |
| position: absolute; |
| width: 50px; |
| height: 30px; |
| left: 50%; |
| top: 50%; |
| margin-left: -25px; |
| margin-top: -15px; |
| } |
| </style> |
| </head> |
| <body> |
| <div id="container" class="narrow"> |
| <button id="target"></button> |
| </div> |
| <script> |
| test( t => { |
| let container = document.querySelector("#container"); |
| let target = document.querySelector("#target"); |
| document.body.offsetTop; |
| // start off narrow |
| let narrow_left = target.offsetLeft; |
| let narrow_top = target.offsetTop; |
| // make it wide |
| container.classList.toggle("narrow"); |
| container.classList.toggle("wide"); |
| document.body.offsetTop; |
| // make it narrow again |
| container.classList.toggle("narrow"); |
| container.classList.toggle("wide"); |
| document.body.offsetTop; |
| assert_equals(target.offsetLeft, narrow_left); |
| assert_equals(target.offsetTop, narrow_top); |
| }, "absolute positioned button with percentage top gets positioned"); |
| </script> |
| </body> |
| </html> |