Snackbar visible when page is overscrolled on Chrome macOS

Do you want to request a feature or report a bug?

Bug

What is the current behavior?

The dismissed snackbar hidden below the page content is visible on Chrome macOS when the page is overscrolled. Not reproducible in Safari.

Previously filed under #723. As @ZhangYiJiang mentioned, this may be related to the upstream bug https://github.com/material-components/material-components-web/issues/1258.

If the current behavior is a bug, please provide the steps to reproduce. If possible, please upload a screenshot or link to a video recording (on macOS you can use QuickTime) demonstrating the problem.

1. Open https://nusmods.com in Chrome on a Mac.
2. Bring up a toast, e.g. by pressing Z or C.
3. Wait until the toast has been dismissed.
4. Scroll beyond the bottom of the page.
5. Observe sneaky, hiding toast.

What is the expected behavior?

Toast should not be visible.

Further information

• Which version of NUSMods are you currently using? 20180217-63f1d4f.
• Which browser and version are you using? Chrome on macOS 64.0.3282.186
• Which device are you using? MacBook Pro
• Which operating system and version are you on? macOS 10.13.3

Reproduce the issue at https://nusmods.com in Chrome on macOS by triggering a toast with Z or C, waiting for dismissal, and overscrolling past the bottom. Compare the behavior with Safari and review upstream material-components/material-components-web#1258; done means the dismissed toast stays invisible during overscroll.