| <!DOCTYPE html> |
| <title>position:sticky elements can be constrained by top and bottom exceeding container size</title> |
| <link rel="help" href="https://www.w3.org/TR/css-position-3/#sticky-pos" /> |
| <meta name="assert" content="This test checks that position:sticky elements obey both top and bottom constraints" /> |
| |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| |
| <style> |
| |
| .scroller { |
| height: 200px; |
| overflow: auto; |
| position: relative; |
| } |
| .container { |
| height: 120px; |
| } |
| .padding, .sticky { |
| height: 50px; |
| } |
| .overflow-padding { |
| height: 200px; |
| } |
| .sticky { |
| position: sticky; |
| background: green; |
| top: -25px; |
| bottom: 150px; |
| } |
| </style> |
| |
| <body> |
| <div class="scroller"> |
| <div class="container"> |
| <div class="padding"></div> |
| <div class="sticky"></div> |
| </div> |
| <div class="overflow-padding"></div> |
| </div> |
| </body> |
| |
| <script> |
| test(() => { |
| const scroller = document.querySelector('.scroller'); |
| const element = document.querySelector('.sticky'); |
| scroller.scrollTop = 0; |
| assert_equals(element.offsetTop, 0); |
| }, 'initially the sticky box should be pushed to the top of the container'); |
| |
| test(() => { |
| const scroller = document.querySelector('.scroller'); |
| const element = document.querySelector('.sticky'); |
| scroller.scrollTop = 95; |
| assert_equals(element.offsetTop, 70); |
| }, 'when we scroll past the flow position the top constraint pushes it down'); |
| </script> |