html {
  height: 100%;
}
body {
  min-height: 100%;
  margin: 0;
  padding: 0;
  position: relative;
}

header {
  background-color: #ffe4c4;
}
/* main { */
  /* padding-bottom: 100px; */
  /* background-color: #bdb76b; */
/* } main的padding-bottom值要等于或大于footer的height值 */
footer {
  position: absolute;
  bottom: 0;
  width: 100%;
  height: 100px;
  background-color: #ffc0cb;
}