我想有两列,第一列是
   
    width: 3rem
   
   ,第二个具有剩余宽度。
  
  
   另外,我希望文本转到下一行,如何使用
   
    flexbox
   
  
  
  
  
   
    .d-flex {
  display: flex !important;
}
.d-inline-block {
  display: inline-block;
}
.text-primary {
  color: white;
}
h2:first-of-type {
 background: blue;
 flex: 0 0 3rem;
}
h2:last-of-type {
  background: red;
  flex: 1;
}
    <div class="d-flex">
  <H2 class="text-primary">1 / </H2>
  <div>
    <H2>Hello World</H2>
    <P>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea</P>
  </div>
</div>