[css] How do you get the footer to stay at the bottom of a Web page?

I have a simple 2-column layout with a footer that clears both the right and left div in my markup. My problem is that I can't get the footer to stay at the bottom of the page in all browsers. It works if the content pushes the footer down, but that's not always the case.

Use CSS vh units!

Probably the most obvious and non-hacky way to go about a sticky footer would be to make use of the new css viewport units.

Take for example the following simple markup:

<header>header goes here</header>
<div class="content">This page has little content</div>
<footer>This is my footer</footer>

If the header is say 80px high and the footer is 40px high, then we can make our sticky footer with one single rule on the content div:

.content {
    min-height: calc(100vh - 120px);
    /* 80px header + 40px footer = 120px  */
}

Which means: let the height of the content div be at least 100% of the viewport height minus the combined heights of the header and footer.

That's it.

* {_x000D_
    margin:0;_x000D_
    padding:0;_x000D_
}_x000D_
header {_x000D_
    background: yellow;_x000D_
    height: 80px;_x000D_
}_x000D_
.content {_x000D_
    min-height: calc(100vh - 120px);_x000D_
    /* 80px header + 40px footer = 120px  */_x000D_
    background: pink;_x000D_
}_x000D_
footer {_x000D_
    height: 40px;_x000D_
    background: aqua;_x000D_
}

<header>header goes here</header>_x000D_
<div class="content">This page has little content</div>_x000D_
<footer>This is my footer</footer>

... and here's how the same code works with lots of content in the content div:

* {_x000D_
    margin:0;_x000D_
    padding:0;_x000D_
}_x000D_
header {_x000D_
    background: yellow;_x000D_
    height: 80px;_x000D_
}_x000D_
.content {_x000D_
    min-height: calc(100vh - 120px);_x000D_
    /* 80px header + 40px footer = 120px  */_x000D_
    background: pink;_x000D_
}_x000D_
footer {_x000D_
    height: 40px;_x000D_
    background: aqua;_x000D_
}

<header>header goes here</header>_x000D_
<div class="content">Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat. Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi. Nam liber tempor cum soluta nobis eleifend option congue nihil imperdiet doming id quod mazim placerat facer possim assum. Typi non habent claritatem insitam; est usus legentis in iis qui facit eorum claritatem. Investigationes demonstraverunt lectores legere me lius quod ii legunt saepius. Claritas est etiam processus dynamicus, qui sequitur mutationem consuetudium lectorum. Mirum est notare quam littera gothica, quam nunc putamus parum claram, anteposuerit litterarum formas humanitatis per seacula quarta decima et quinta decima. Eodem modo typi, qui nunc nobis videntur parum clari, fiant sollemnes in futurum.Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat. Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi. Nam liber tempor cum soluta nobis eleifend option congue nihil imperdiet doming id quod mazim placerat facer possim assum. Typi non habent claritatem insitam; est usus legentis in iis qui facit eorum claritatem. Investigationes demonstraverunt lectores legere me lius quod ii legunt saepius. Claritas est etiam processus dynamicus, qui sequitur mutationem consuetudium lectorum. Mirum est notare quam littera gothica, quam nunc putamus parum claram, anteposuerit litterarum formas humanitatis per seacula quarta decima et quinta decima. Eodem modo typi, qui nunc nobis videntur parum clari, fiant sollemnes in futurum._x000D_
</div>_x000D_
<footer>_x000D_
    This is my footer_x000D_
</footer>

NB:

1) The height of the header and footer must be known

2) Old versions of IE (IE8-) and Android (4.4-) don't support viewport units. (caniuse)

3) Once upon a time webkit had a problem with viewport units within a calc rule. This has indeed been fixed (see here) so there's no problem there. However if you're looking to avoid using calc for some reason you can get around that using negative margins and padding with box-sizing -

Like so:

* {_x000D_
    margin:0;padding:0;_x000D_
}_x000D_
header {_x000D_
    background: yellow;_x000D_
    height: 80px;_x000D_
    position:relative;_x000D_
}_x000D_
.content {_x000D_
    min-height: 100vh;_x000D_
    background: pink;_x000D_
    margin: -80px 0 -40px;_x000D_
    padding: 80px 0 40px;_x000D_
    box-sizing:border-box;_x000D_
}_x000D_
footer {_x000D_
    height: 40px;_x000D_
    background: aqua;_x000D_
}

<header>header goes here</header>_x000D_
<div class="content">Lorem ipsum _x000D_
</div>_x000D_
<footer>_x000D_
    This is my footer_x000D_
</footer>

Here is a solution with jQuery that works like a charm. It checks if the height of the window is greater than the height of the body. If it is, then it changes the margin-top of the footer to compensate. Tested in Firefox, Chrome, Safari and Opera.

$( function () {

    var height_diff = $( window ).height() - $( 'body' ).height();
    if ( height_diff > 0 ) {
        $( '#footer' ).css( 'margin-top', height_diff );
    }

});

If your footer already has a margin-top (of 50 pixels, for example) you will need to change the last part for:

css( 'margin-top', height_diff + 50 )

jQuery CROSS BROWSER CUSTOM PLUGIN - $.footerBottom()

Or use jQuery like I do, and set your footer height to auto or to fix, whatever you like, it will work anyway. this plugin uses jQuery selectors so to make it work, you will have to include the jQuery library to your file.

Here is how you run the plugin. Import jQuery, copy the code of this custom jQuery plugin and import it after importing jQuery! It is very simple and basic, but important.

When you do it, all you have to do is run this code:

$.footerBottom({target:"footer"}); //as html5 tag <footer>.
// You can change it to your preferred "div" with for example class "footer" 
// by setting target to {target:"div.footer"}

there is no need to place it inside the document ready event. It will run well as it is. It will recalculate the position of your footer when the page is loaded and when the window get resized.

Here is the code of the plugin which you do not have to understand. Just know how to implement it. It does the job for you. However, if you like to know how it works, just look through the code. I left comments for you.

//import jQuery library before this script

// Import jQuery library before this script_x000D_
_x000D_
// Our custom jQuery Plugin_x000D_
(function($) {_x000D_
  $.footerBottom = function(options) { // Or use "$.fn.footerBottom" or "$.footerBottom" to call it globally directly from $.footerBottom();_x000D_
    var defaults = {_x000D_
      target: "footer",_x000D_
      container: "html",_x000D_
      innercontainer: "body",_x000D_
      css: {_x000D_
        footer: {_x000D_
          position: "absolute",_x000D_
          left: 0,_x000D_
          bottom: 0,_x000D_
        },_x000D_
_x000D_
        html: {_x000D_
          position: "relative",_x000D_
          minHeight: "100%"_x000D_
        }_x000D_
      }_x000D_
    };_x000D_
_x000D_
    options = $.extend(defaults, options);_x000D_
_x000D_
    // JUST SET SOME CSS DEFINED IN THE DEFAULTS SETTINGS ABOVE_x000D_
    $(options.target).css({_x000D_
      "position": options.css.footer.position,_x000D_
      "left": options.css.footer.left,_x000D_
      "bottom": options.css.footer.bottom,_x000D_
    });_x000D_
_x000D_
    $(options.container).css({_x000D_
      "position": options.css.html.position,_x000D_
      "min-height": options.css.html.minHeight,_x000D_
    });_x000D_
_x000D_
    function logic() {_x000D_
      var footerOuterHeight = $(options.target).outerHeight(); // Get outer footer height_x000D_
      $(options.innercontainer).css('padding-bottom', footerOuterHeight + "px"); // Set padding equal to footer height on body element_x000D_
      $(options.target).css('height', footerOuterHeight + "!important"); // Set outerHeight of footer element to ... footer_x000D_
      console.log("jQ custom plugin footerBottom runs"); // Display text in console so ou can check that it works in your browser. Delete it if you like._x000D_
    };_x000D_
_x000D_
    // DEFINE WHEN TO RUN FUNCTION_x000D_
    $(window).on('load resize', function() { // Run on page loaded and on window resized_x000D_
      logic();_x000D_
    });_x000D_
_x000D_
    // RETURN OBJECT FOR CHAINING IF NEEDED - IF NOT DELETE_x000D_
    // return this.each(function() {_x000D_
    //   this.checked = true;_x000D_
    // });_x000D_
    // return this;_x000D_
  };_x000D_
})(jQuery); // End of plugin_x000D_
_x000D_
_x000D_
// USE EXAMPLE_x000D_
$.footerBottom(); // Run our plugin with all default settings for HTML5

/* Set your footer CSS to what ever you like it will work anyway */_x000D_
footer {_x000D_
  box-sizing: border-box;_x000D_
  height: auto;_x000D_
  width: 100%;_x000D_
  padding: 30px 0;_x000D_
  background-color: black;_x000D_
  color: white;_x000D_
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
_x000D_
<!-- The structure doesn't matter much, you will always have html and body tag, so just make sure to point to your footer as needed if you use html5, as it should just do nothing run plugin with no settings it will work by default with the <footer> html5 tag -->_x000D_
<body>_x000D_
  <div class="content">_x000D_
  <header>_x000D_
    <nav>_x000D_
      <ul>_x000D_
        <li>link</li>_x000D_
        <li>link</li>_x000D_
        <li>link</li>_x000D_
        <li>link</li>_x000D_
        <li>link</li>_x000D_
        <li>link</li>_x000D_
      </ul>_x000D_
    </nav>_x000D_
  </header>_x000D_
_x000D_
  <section>_x000D_
      <p></p>_x000D_
      <p>Lorem ipsum...</p>_x000D_
    </section>_x000D_
  </div>_x000D_
  <footer>_x000D_
    <p>Copyright 2009 Your name</p>_x000D_
    <p>Copyright 2009 Your name</p>_x000D_
    <p>Copyright 2009 Your name</p>_x000D_
  </footer>

New and Simpler Solution

I found a very clean way to solve this using Flexbox.

1. Style parent like this:

   display: flex;
   flex-direction: column;
   flex: 1;
   min-height: 100vh;
   

2. Style footer margin-top: auto.

3. That's it!

Demo: https://codepen.io/ferittuncer/pen/Pozdxdm

Old Solution

index.html:

<!DOCTYPE html>

<html>
 <head>
   <link rel="stylesheet" type="text/css" href="main.css" />
 </head>

<body>
 <div id="page-container">
   <div id="content-wrap">
     <!-- all other page content -->
   </div>
   <footer id="footer"></footer>
 </div>
</body>

</html>

main.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 */
}

Source: https://www.freecodecamp.org/news/how-to-keep-your-footer-where-it-belongs-59c6aa05c59c/

REACT-friendly solution - (no spacer div required)

Chris Coyier (the venerable CSS-Tricks website) has kept his page on the Sticky-Footer up-to-date, with at least FIVE methods now for creating a sticky footer, including using FlexBox and CSS-Grid.

Why is this important? Because, for me, the earlier/older methods I used for years did not work with React - I had to use Chris' flexbox solution - which was easy and worked.

Below is his CSS-Tricks flexbox Sticky Footer - just look at the code below, it cannot possibly be simpler.

(The (below) StackSnippet example does not perfectly render the bottom of the example. The footer is shown extending past the bottom of the screen, which does not happen in real life.)

html,body{height: 100%;}
body     {display:flex; flex-direction:column;}
.content {flex: 1 0 auto;} /* flex: grow / shrink / flex-basis; */
.footer  {flex-shrink: 0;}

/* ---- BELOW IS ONLY for demo ---- */
.footer{background: palegreen;}

<body>
  <div class="content">Page Content - height expands to fill space</div>
  <footer class="footer">Footer Content</footer>
</body>

Chris also demonstrates this CSS-Grid solution for those who prefer grid.

References:

CSS-Tricks - A Complete Guide to Flexbox

None of these pure css solutions work properly with dynamically resizing content (at least on firefox and Safari) e.g., if you have a background set on the container div, the page and then resize (adding a few rows) table inside the div, the table can stick out of the bottom of the styled area, i.e., you can have half the table in white on black theme and half the table complete white because both the font-color and background color is white. It's basically unfixable with themeroller pages.

Nested div multi-column layout is an ugly hack and the 100% min-height body/container div for sticking footer is an uglier hack.

The only none-script solution that works on all the browsers I've tried: a much simpler/shorter table with thead (for header)/tfoot (for footer)/tbody (td's for any number of columns) and 100% height. But this have perceived semantic and SEO disadvantages (tfoot must appear before tbody. ARIA roles may help decent search engines though).

Since the Grid solution hasn't been presented yet, here it is, with just two declarations for the parent element, if we take the height: 100% and margin: 0 for granted:

html, body {height: 100%}_x000D_
_x000D_
body {_x000D_
  display: grid; /* generates a block-level grid */_x000D_
  align-content: space-between; /* places an even amount of space between each grid item, with no space at the far ends */_x000D_
  margin: 0;_x000D_
}_x000D_
_x000D_
.content {_x000D_
  background: lightgreen;_x000D_
  /* demo / for default snippet window */_x000D_
  height: 1em;_x000D_
  animation: height 2.5s linear alternate infinite;_x000D_
}_x000D_
_x000D_
footer {background: lightblue}_x000D_
_x000D_
@keyframes height {to {height: 250px}}

<div class="content">Content</div>_x000D_
<footer>Footer</footer>

• align-content: space-between

The items are evenly distributed within the alignment container along the cross axis. The spacing between each pair of adjacent items is the same. The first item is flush with the main-start edge, and the last item is flush with the main-end edge.

I have created a very simple library https://github.com/ravinderpayal/FooterJS

It is very simple in use. After including library, just call this line of code.

footer.init(document.getElementById("ID_OF_ELEMENT_CONTAINING_FOOTER"));

Footers can be dynamically changed by recalling above function with different parameter/id.

footer.init(document.getElementById("ID_OF_ANOTHER_ELEMENT_CONTAINING_FOOTER"));

Note:- You haven't to alter or add any CSS. Library is dynamic which implies that even if screen is resized after loading page it will reset the position of footer. I have created this library, because CSS solves the problem for a while but when size of display changes significantly,from desktop to tablet or vice versa, they either overlap the content or they no longer remains sticky.

Another solution is CSS Media Queries, but you have to manually write different CSS styles for different size of screens while this library does its work automatically and is supported by all basic JavaScript supporting browser.

Edit CSS solution:

@media only screen and (min-height: 768px) {/* or height/length of body content including footer*/
    /* For mobile phones: */
    #footer {
        width: 100%;
        position:fixed;
        bottom:0;
    }
}

Now, if the height of display is more than your content length, we will make footer fixed to bottom and if not, it will automatically appear in very end of display as you need to scroll to view this.

And, it seems a better solution than JavaScript/library one.

If you don't want it using position fixed, and following you annoyingly on mobile, this seems to be working for me so far.

html {
    min-height: 100%;
    position: relative;
}

#site-footer {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    padding: 6px 2px;
    background: #32383e;
}

Just set the html to min-height: 100%; and position: relative;, then position: absolute; bottom: 0; left: 0; on the footer. I then made sure the footer was the last element in the body.

Let me know if this doesn't work for anyone else, and why. I know these tedious style hacks can behave strangely among various circumstances I'd not thought of.

Set the CSS for the #footer to:

position: absolute;
bottom: 0;

You will then need to add a padding or margin to the bottom of your #sidebar and #content to match the height of #footer or when they overlap, the #footer will cover them.

Also, if I remember correctly, IE6 has a problem with the bottom: 0 CSS. You might have to use a JS solution for IE6 (if you care about IE6 that is).

For me the nicest way of displaying it (the footer) is sticking to the bottom but not covering content all the time:

#my_footer {
    position: static
    fixed; bottom: 0
}

I have myself struggled with this sometimes and I always found that the solution with all those div's within each other was a messy solution. I just messed around with it a bit, and I personally found out that this works and it certainly is one of the simplest ways:

html {
    position: relative;
}

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

footer {
    position: absolute;
    bottom: 0;
}

What I like about this is that no extra HTML needs to be applied. You can simply add this CSS and then write your HTML as whenever

For this question many of the answers I have seen are clunky, hard to implement and inefficient so I thought I'd take a shot at it and come up with my own solution which is just a tiny bit of css and html

html,_x000D_
body {_x000D_
  height: 100%;_x000D_
  margin: 0;_x000D_
}_x000D_
.body {_x000D_
  min-height: calc(100% - 2rem);_x000D_
  width: 100%;_x000D_
  background-color: grey;_x000D_
}_x000D_
.footer {_x000D_
  height: 2rem;_x000D_
  width: 100%;_x000D_
  background-color: yellow;_x000D_
}

<body>_x000D_
  <div class="body">test as body</div>_x000D_
  <div class="footer">test as footer</div>_x000D_
</body>

this works by setting the height of the footer and then using css calc to work out the minimum height the page can be with the footer still at the bottom, hope this helps some people :)

The flex solutions worked for me as far as making the footer sticky, but unfortunately changing the body to use flex layout made some of our page layouts change, and not for the better. What finally worked for me was:

    jQuery(document).ready(function() {

    var fht = jQuery('footer').outerHeight(true);
    jQuery('main').css('min-height', "calc(92vh - " + fht + "px)");

});

I got this from ctf0's response at https://css-tricks.com/couple-takes-sticky-footer/

Try putting a container div (with overflow:auto) around the content and sidebar.

If that doesn't work, do you have any screenshots or example links where the footer isn't displayed properly?

CSS :

  #container{
            width: 100%;
            height: 100vh;
            }
 #container.footer{
            float:left;
            width:100%;
            height:20vh;
            margin-top:80vh;
            background-color:red;
            }

HTML:

           <div id="container">
               <div class="footer">
               </div>
           </div>

This should do the trick if you are looking for a responsive footer aligned at the bottom of the page,which always keeps a top-margin of 80% of the viewport height.

One solution would be to set the min-height for the boxes. Unfortunately it seems that it's not well supported by IE (surprise).

Flexbox solution

Flex layout is preferred for natural header and footer heights. This flex solution is tested in modern browsers and actually works :) in IE11.

See JS Fiddle.

HTML

<body>
  <header>
    ...
  </header>
  <main>
    ...
  </main>
  <footer>
    ...
  </footer>
</body>  

CSS

html {
  height: 100%;
}

body {
  height: 100%;
  min-height: 100vh;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  margin: 0;
  display: flex;
  flex-direction: column;
}

main {
  flex-grow: 1;
  flex-shrink: 0;
}

header,
footer {
  flex: none;
}

I wasn't having any luck with the solutions suggested on this page before but then finally, this little trick worked. I'll include it as another possible solution.

footer {
  position: fixed;
  right: 0;
  bottom: 0;
  left: 0;
  padding: 1rem;
  background-color: #efefef;
  text-align: center;
}

Sticky footer with display: flex

Solution inspired by Philip Walton's sticky footer.

Explanation

This solution is valid only for:

• Chrome = 21.0
• Firefox = 20.0
• Internet Explorer = 10
• Safari = 6.1

It is based on the flex display, leveraging the flex-grow property, which allows an element to grow in either height or width (when the flow-direction is set to either column or row respectively), to occupy the extra space in the container.

We are going to leverage also the vh unit, where 1vh is defined as:

1/100th of the height of the viewport

Therefore a height of 100vh it's a concise way to tell an element to span the full viewport's height.

This is how you would structure your web page:

----------- body -----------
----------------------------

---------- footer ----------
----------------------------

In order to have the footer stick to the bottom of the page, you want the space between the body and the footer to grow as much as it takes to push the footer at the bottom of the page.

Therefore our layout becomes:

----------- body -----------
----------------------------

---------- spacer ----------
                             <- This element must grow in height
----------------------------

---------- footer ----------
----------------------------

Implementation

body {
    margin: 0;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.spacer {
    flex: 1;
}

/* make it visible for the purposes of demo */
.footer {
    height: 50px;
    background-color: red;
}

<body>
    <div class="content">Hello World!</div>
    <div class="spacer"></div>
    <footer class="footer"></footer>
</body>

You can play with it at the JSFiddle.

Safari quirks

Be aware that Safari has a flawed implementation of the flex-shrink property, which allows items to shrink more than the minimum height that would be required to display the content. To fix this issue you will have to set the flex-shrink property explicitly to 0 to the .content and the footer in the above example:

.content {
  flex-shrink: 0;
}

.footer {
  flex-shrink: 0;
}

Alternatively, change the flex style for the spacer element into:

.spacer {
  flex: 1 0 auto;
}

This 3-value shorthand style is equivalent to the following full setup:

.spacer {
  flex-grow: 1;
  flex-shrink: 0;
  flex-basis: auto;
}

Elegantly works everywhere.

An old thread I know, but if you are looking for a responsive solution, this jQuery addition will help:

$(window).on('resize',sticky);
$(document).bind("ready", function() {
   sticky();
});

function sticky() {
   var fh = $("footer").outerHeight();
   $("#push").css({'height': fh});
   $("#wrapper").css({'margin-bottom': -fh});
}

Full guide can be found here: https://pixeldesigns.co.uk/blog/responsive-jquery-sticky-footer/

Have a look at http://1linelayouts.glitch.me/, example 4. Una Kravets nails this problem.

This creates a 3 layer page with header, main and footer.

-Your footer will always stay at the bottom, and use space to fit the content;

-Your header will always stay at the top, and use space to fit the content;

-Your main will always use all the available remaining space (remaining fraction of space), enough to fill the screen, if need.

HTML

<div class="parent">
  <header class="blue section" contenteditable>Header</header>
  <main class="coral section" contenteditable>Main</main>
  <footer class="purple section" contenteditable>Footer Content</footer>
</div>
    

CSS

.parent {
  display: grid;
  height: 95vh; /* no scroll bars if few content */
  grid-template-rows: auto 1fr auto;
}
    

You could use position: absolute following to put the footer at the bottom of the page, but then make sure your 2 columns have the appropriate margin-bottom so that they never get occluded by the footer.

#footer {
    position: absolute;
    bottom: 0px;
    width: 100%;
}
#content, #sidebar { 
    margin-bottom: 5em; 
}

Use absolute positioning and z-index to create a sticky footer div at any resolution using the following steps:

• Create a footer div with position: absolute; bottom: 0; and the desired height
• Set the padding of the footer to add whitespace between the content bottom and the window bottom
• Create a container div that wraps the body content with position: relative; min-height: 100%;
• Add bottom padding to the main content div that is equal to the height plus padding of the footer
• Set the z-index of the footer greater than the container div if the footer is clipped

Here is an example:

<!doctype html>
<html>
  <head>
    <title>Sticky Footer</title>
    <meta charset="utf-8">
    <style>
      .wrapper { position: relative; min-height: 100%; }
      .footer { position: absolute; bottom:0; width: 100%; height: 200px; padding-top: 100px; background-color: gray; }
      .column { height: 2000px; padding-bottom: 300px; background-color: grxqeen; }
      /* Set the `html`, `body`, and container `div` to `height: 100%` for IE6 */
    </style>
  </head>
  <body>
    <div class="wrapper">
      <div class="column">
        <span>hello</span>
      </div>
      <div class="footer">
        <p>This is a test. This is only a test...</p>
      </div>
    </div>
  </body>
</html>

Multiple people have put the answer to this simple problem up here, but I have one thing to add, considering how frustrated I was until I figured out what I was doing wrong.

As mentioned the most straightforward way to do this is like so..

html {
    position: relative;
    min-height: 100%;
}

body {
    background-color: transparent;
    position: static;
    height: 100%;
    margin-bottom: 30px;
}

.site-footer {
    position: absolute;
    height: 30px;
    bottom: 0px;
    left: 0px;
    right: 0px;
}

However the property not mentioned in posts, presumably because it is usually default, is the position: static on the body tag. Position relative will not work!

My wordpress theme had overridden the default body display and it confused me for an obnoxiously long time.

A similar solution to @gcedo but without the need of adding an intermediate content in order to push the footer down. We can simply add margin-top:auto to the footer and it will be pushed to the bottom of the page regardless his height or the height of the content above.

body {_x000D_
  display: flex;_x000D_
  flex-direction: column;_x000D_
  min-height: 100vh;_x000D_
  margin:0;_x000D_
}_x000D_
_x000D_
.content {_x000D_
  padding: 50px;_x000D_
  background: red;_x000D_
}_x000D_
_x000D_
.footer {_x000D_
  margin-top: auto;_x000D_
  padding:10px;_x000D_
  background: green;_x000D_
}

<div class="content">_x000D_
  some content here_x000D_
</div>_x000D_
<footer class="footer">_x000D_
  some content_x000D_
</footer>