Vertical scrollbar appears when the container has height set to 100%

[Comandeer]

Type of report

Bug

Provide detailed reproduction steps (if any)

1. Open https://codepen.io/Comandeer/full/GRBjMWJ

Expected result

There is no vertical scrollbar

Actual result

There is a vertical scrollbar.

Other details

• Browser: Blink-based and Safari
• OS: N/A
• CKEditor version: 4.7.0+
• Installed CKEditor plugins: copyformatting

The issue is connected with the fact that the .cke_screen_reader_only element, used for Copy Formatting notifications, has non-zero dimensions. Somehow it forces the scrollbar if the editor's container has the same height as the viewport. We should check if we could change the dimensions of the notifications element to 0 without affecting screen readers.

It could be also a good moment to align our screen reader utility class with the industry standard.

[Comandeer]

There is a proposed workaround in the ZK CKeditor issue tracker:

.cke_screen_reader_only {
    bottom: 0px;
}

It's worth checking if it's enough and does not cause any issue with screen readers.