how to set footer fixed to bottom code example

Example 1: how to get my footer to the bottom of the page using css

#page-container {
  position: relative;
  min-height: 100vh;
}

#content-wrap {
  padding-bottom: 2.5rem;    /* Footer height */
}

#footer {
  position: absolute;
  bottom: 0;
  width: 100%;
  height: 2.5rem;            /* Footer height */
}

Example 2: sticky footer bootstrap 3

<style>
.footer {
   position: fixed;
   left: 0;
   bottom: 0;
   width: 100%;
   background-color: red;
   color: white;
   text-align: center;
}
</style>