A combination of positioning styles included with this block causes layout issues with the parent Editor.js, even when the Columns tool is not enabled. I believe the cause to be these two lines:
https://github.com/calumk/editorjs-columns/blob/79d6e2f/src/editorjs-columns.scss#L56
https://github.com/calumk/editorjs-columns/blob/79d6e2f/src/editorjs-columns.scss#L61
Together, they first shift the initial input point to the left from the default center and then cause the tool bar to clip out of the page to the left:

A combination of positioning styles included with this block causes layout issues with the parent Editor.js, even when the Columns tool is not enabled. I believe the cause to be these two lines:
https://github.com/calumk/editorjs-columns/blob/79d6e2f/src/editorjs-columns.scss#L56
https://github.com/calumk/editorjs-columns/blob/79d6e2f/src/editorjs-columns.scss#L61
Together, they first shift the initial input point to the left from the default center and then cause the tool bar to clip out of the page to the left: