how to make footer stick to the bottom of the page code example

Example 1: html make footer stick to bottom

body{
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}
footer{
    margin-top: auto;
}

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>