css如何让高度自适应

html {
  height: 100%;
  display: table;
}

body {
  display: table-cell;
  height: 100%;
}

<div class="container">
  <header></header>
  <content></content>
  <footer></footer>
</div>

.container {
  display: flex;
  min-height: 100vh;
  flex-direction: column;
}

header {
  background: #cecece;
  min-height: 100px;
}

content {
  background: #bbbbbb;
  flex: 1; /* 1 代表盡可能最大，會自動填滿除了 header footer 以外的空間 */
}

footer {
  background: #333333;
  min-height: 100px;
}

$(document).ready(function(){
  var windowHeight = $(window).height();
  if($(this).height() < windowHeight){
      $(this).height(windowHeight);
  }
});

window.onload = function(){
  var winHeight = 0;
  if (window.innerHeight){
    winHeight = window.innerHeight;
  }else if ((document.body) && (document.body.clientHeight)){
    winHeight = document.body.clientHeight;
  }
  var html = document.getElementsByTagName('html')[0];
  if(document.body.offsetHeight < windowHeight){
      html.style.height = windowHeight;
  }
};