How do making fixed footer with css or HTML?

Answer 1

You can achieve that with css layout using position property.
position: fixed
If you want to learn more about it: http://www.w3schools.com/css/css_positioning.asp

Answer 2

https://code.sololearn.com/WAEqp08z299b/#html
Note, that top and margin-top of footer are equal, except margin-top is negative

Answer 3

There are many ways to achieve that. Probably the best option is position: fixed. Other option is e.g. position: absolute; bottom: 0; But keep in mind you have to solve potential problems with overlapping the page content, position, responsive design etc. I would recommend using the position: fixed property together with flex or margin: auto; properties. Everything depends on the expected result ;-)