title: Safari grid in flexbox produces height overflow
body: <p>My whole page is in flex, most of the elements are positioned with flex (rather than <code>height: 100%</code> I tend to use <code>flex: 1</code>). Later I wanted to introduce grid in more complicated component, and that grid will consist of two rows of given ratio (1:2).</p>
  
  <p>This is the result I expected (and it is screenshot from Chrome), where pink and red boxes are in 1:2 ratio:
  <a href="https://i.stack.imgur.com/KcDaa.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KcDaa.png" alt="screenshot from Chrome"></a></p>
  
  <p>And this is the result that Safari is producing:</p>
  
  <p><a href="https://i.stack.imgur.com/rTEOR.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rTEOR.png" alt="enter image description here"></a></p>
  
  <p>I am quite speechless.</p>
  
  <p><a href="https://codesandbox.io/s/charming-bird-n112l?file=/index.html" rel="nofollow noreferrer">https://codesandbox.io/s/charming-bird-n112l?file=/index.html</a></p>