Tab cannot be aligned if there is Chinese character in its left-side

[cyfung1031]

\t\t你
\t你\t你
 你。\t你
\t\tu
\tu\tu
 u.\tu

https://codemirror.net/5/demo/theme.html

[cyfung1031]

I found a solution using CSS.
In my case, I just have one tab in one row.
I used createMode that enclose the word including the tab in every row.
I set the enclosing span as display:inline-flex; width:12em; flex-direction: row then problem solved.
The .cm-tab will automatically grow to fill up the remaining space of the enclosing span.