Html 如何动态调整彼此重叠的两个 div 的大小，使它们在增长时保持相同的高度

.container {
  display: grid;
  grid-template-rows: 1fr 1fr;
  margin-bottom: 25px;
}

.b1 {
  background-color: red;
}

.b2 {
  background-color: orange;
}

body {
  margin: 0
}

<div class="container">
  <div class="box b1">One</div>
  <div class="box b2">
    DIV B Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.
    It has survived not only five centecently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
  </div>
</div>

<div class="container">
  <div class="box b1">One</div>
  <div class="box b2">
    DIV B Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.
    It has survived not only five centecently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.
    It has survived not only five centecently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
  </div>
</div>

const container = document.querySelector('.container');
const b1 = document.querySelector('.b1');
const b2 = document.querySelector('.b2');

function setHeight() {
  const b2Height = b2.offsetHeight;
  b1.style.height = `${b2Height}px`;
}

window.addEventListener('resize', setHeight);
setHeight();

.container {
    display: flex;
    flex-direction: column;
  }

  .b1 {
    background-color: red;
    height: 50%;
  }

  .b2 {
    background-color: orange;
    height: 50%;
  }

  .box {
    flex-grow: 1;
  }

<div class="container">
  <div class="box b1">One</div>
  <div class="box b2">
    DIV B Lorem Ipsum is simply dummy text of the printing and typesetting
    industry. Lorem Ipsum has been the industry's standard dummy text ever since
    the 1500s, when an unknown printer took a galley of type and scrambled it to
    make a type specimen book. It has survived not only five centuries, but also
    the leap into electronic typesetting, remaining essentially unchanged. It
    was popularised in the 1960s with the release of Letraset sheets containing
    Lorem Ipsum passages, and more recently with desktop publishing software
    like Aldus PageMaker including versions of Lorem Ipsum.
  </div>
</div>