change getBoundingClientRect from offsetwidth

[NaokiFujikawa]

"offsetwidth" is round the value to an intege. So I want you to use "getBoundingClientRect".

https://developer.mozilla.org/ja/docs/Web/API/Element/getBoundingClientRect

The same thing happens with the issue below in the scroll view.
ant-design/ant-design#25300 (comment)

[wubostc]

@NaokiFujikawa
i will pay attention to this issue

[wubostc]

@NaokiFujikawa
i will pay attention to this issue

can you put some examples on https://codesandbox.io which can show the differences that you said.

[NaokiFujikawa]

Thank you for your interest.
I made a sample for you. https://codesandbox.io/s/pull73-forked-oscod

This is caused by changing the display settings
The differences in the display settings are shown below.

When the display setting is 100%, there is no problem.

But it occurs when you set it to 125%. The scroll bar will be active.

[wubostc]

this commit has a big problem...
it will cause the height of each tr to be increased by 1

[wubostc]

the main problem at present is that there is no way to set a floating-number for css...

[NaokiFujikawa]

Thank you for checking.

I see. I'm fine in my use, but I didn't think about PR.