how to make footer part of the viewport code example

Example 1: push footer to bottom

.flex-wrapper {
  display: flex;
  min-height: 100vh;
  flex-direction: column;
  justify-content: space-between
}

Example 2: keep footer at bottom of page

#footer {
  position: relative;
  margin-top: -180px;
  /* negative value of footer height */
  height: 180px;
  clear: both;
 /*Custom styling*/
}

/* Opera Fix thanks to Maleika (Kohoutec) */

body:before {
  content: "";
  height: 100%;
  float: left;
  width: 0;
  margin-top: -32767px;
  /* thank you Erik J - negate effect of float*/
}