| <!DOCTYPE html> |
| <title>position:sticky elements should respect padding on their ancestor overflow element</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 respect padding on their ancestor overflow element" /> |
| |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| |
| <script src="resources/sticky-util.js"></script> |
| |
| <body></body> |
| |
| <script> |
| test(() => { |
| const elements = setupStickyTest('top', 50); |
| elements.scroller.style.padding = '20px 0'; |
| |
| // Before sticking; the element isn't within the padding range. |
| elements.scroller.scrollTop = 150; |
| const nonStickyTopY = elements.container.offsetTop + |
| elements.filler.clientHeight; |
| assert_equals(elements.sticky.offsetTop, nonStickyTopY); |
| }, 'A sticky element should not be affected by ancestor padding until it ' + |
| 'reaches it'); |
| |
| test(() => { |
| const elements = setupStickyTest('top', 50); |
| elements.sticky.style.top = '0'; |
| elements.scroller.style.padding = '20px 0'; |
| |
| elements.scroller.scrollTop = 200; |
| |
| // This math cancels to sticky.offsetTop == (scroller.scrollTop + 50), but |
| // for clarity the calculations are left explicit. |
| const nonStickyTopY = elements.container.offsetTop + |
| elements.filler.clientHeight; |
| const targetTopY = elements.scroller.scrollTop; |
| const stickyOffset = targetTopY - nonStickyTopY; |
| |
| assert_equals(elements.sticky.offsetTop, nonStickyTopY + stickyOffset + 20); |
| }, 'A sticky element should be offset by ancestor padding even when stuck'); |
| |
| test(() => { |
| const elements = setupStickyTest('top', 50); |
| elements.sticky.style.top = '0'; |
| elements.scroller.style.padding = '20px 0'; |
| |
| elements.scroller.scrollTop = 315; |
| const maxOffsetInContainer = elements.container.offsetTop + |
| elements.container.clientHeight - elements.sticky.clientHeight; |
| assert_equals(elements.sticky.offsetTop, maxOffsetInContainer); |
| }, 'Ancestor overflow padding does not allow a sticky element to escape its ' + |
| 'container'); |
| </script> |
