Here's a screencast illustrating what I mentioned in comment 4. Watch the margin-bottom values that get (briefly) applied to the `header` element as I resize the window -- they're often on the order of 19,000px. At the end of the video, I manually add `margin-bottom:19000px` and you can see that this does indeed make all the content disappear.
Bug 1830307 Comment 5 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
Here's a screencast illustrating what I mentioned in comment 4. Watch the margin-bottom values that get (briefly) applied to the `header` element as I resize the window -- they're often on the order of 19,000px. At the end of the video, I manually add `margin-bottom:-19000px` and you can see that this does indeed make all the content disappear.