Canvas on Chart.js resizing in flexbox?

Question

Canvas

Others tell me. I have a frame like this:

<div style="display: flex;">
  <div id=1 style="flex-grow: 0.75;"><canvas id=some_id></div>
  <div id=2 style="flex-grow: 0.25;">...</div>
</div>

canvas - chart on Chart.js
When the page expands, the canvas increases, and when the page width decreases, it does not change. How to be?