Css: Fixed to Bottom and Centered

CSS: How to center a bottom-fixed menu

To center an element you need to specify width and set left and right margins to auto.
Then to stick such an element to the bottom of the page you need to wrap it in another element which has fixed width, say 100% and is positioned on the bottom. And yes, css you can.

<section style="position: fixed; bottom: 0px; width: 100%;">
 <p style="margin: 0 auto; width: 300px;">Blah blah</p>
</section>

CSS: fixed to bottom and centered

You should use a sticky footer solution such as this one :

* {
    margin: 0;
}
html, body {
    height: 100%;
}
.wrapper {
    min-height: 100%;
    height: auto !important;
    height: 100%;
    margin: 0 auto -142px; /* the bottom margin is the negative value of the footer's height */
}
.footer, .push {
    height: 142px; /* .push must be the same height as .footer */
}

There are others like this;

* {margin:0;padding:0;} 

/* must declare 0 margins on everything, also for main layout components use padding, not 
vertical margins (top and bottom) to add spacing, else those margins get added to total height 
and your footer gets pushed down a bit more, creating vertical scroll bars in the browser */

html, body, #wrap {height: 100%;}

body > #wrap {height: auto; min-height: 100%;}

#main {padding-bottom: 150px;}  /* must be same height as the footer */

#footer {position: relative;
    margin-top: -150px; /* negative value of footer height */
    height: 150px;
    clear:both;} 

/* CLEAR FIX*/
.clearfix:after {content: ".";
    display: block;
    height: 0;
    clear: both;
    visibility: hidden;}
.clearfix {display: inline-block;}
/* Hides from IE-mac \*/
* html .clearfix { height: 1%;}
.clearfix {display: block;}

with the html:

<div id="wrap">

    <div id="main" class="clearfix">

    </div>

</div>

<div id="footer">

</div>

Center a position:fixed element

You basically need to set top and left to 50% to center the left-top corner of the div. You also need to set the margin-top and margin-left to the negative half of the div's height and width to shift the center towards the middle of the div.

Thus, provided a <!DOCTYPE html> (standards mode), this should do:

position: fixed;
width: 500px;
height: 200px;
top: 50%;
left: 50%;
margin-top: -100px; /* Negative half of height. */
margin-left: -250px; /* Negative half of width. */

Or, if you don't care about centering vertically and old browsers such as IE6/7, then you can instead also add left: 0 and right: 0 to the element having a margin-left and margin-right of auto, so that the fixed positioned element having a fixed width knows where its left and right offsets start. In your case thus:

position: fixed;
width: 500px;
height: 200px;
margin: 5% auto; /* Will not center vertically and won't work in IE6/7. */
left: 0;
right: 0;

Again, this works only in IE8+ if you care about IE, and this centers only horizontally not vertically.

How do I position a div at the bottom center of the screen

align="center" has no effect.

Since you have position:absolute, I would recommend positioning it 50% from the left and then subtracting half of its width from its left margin.

#manipulate {
    position:absolute;
    width:300px;
    height:300px;
    background:#063;
    bottom:0px;
    right:25%;
    left:50%;
    margin-left:-150px;
}

Cant center a div in CSS (BANNER FIXED AT BOTTOM)

I have added div#fragment inside a div which has 100% width.And within that div, div#fragment is centered aligned. I have made some modifications in CSS.
Please check the code snippet as follows:

/* Styles go here */
#fragment {  font-size: 12px;  font-family: tahoma;  border: 1px solid #ccc;  color: #555;  display: block;  box-sizing: border-box;  text-decoration: none;  min-height: 50px;  width: 300px;  overflow: hidden;  margin-left: auto;  margin-right: auto;}
#fragment:hover {  box-shadow: 2px 2px 5px rgba(0, 0, 0, .2);}
.row {  text-align: center;  position: fixed;  bottom: 0;  min-width: 100%;}
.item-right {  text-align: right;}
#close {  display: inline-block;  padding: 2px 5px;  background: #ccc;}
#close:hover {  display: inline-block;  padding: 2px 5px;  background: #ccc;  color: #fff;  cursor: pointer;}

<!DOCTYPE html><html>
<head>  <link rel="stylesheet" href="style.css"></head>
<body>  <div class="row">    <div id="fragment" class="item-right">      <span id="close" onclick="this.parentElement.style.display='none';">x</span>    </div>  </div></body>
</html>

How to make the footer stick to the bottom of the page and centered in Bootstrap?

The simple way is to use flexbox on the BODY or some wrapper element. Then use mt-auto to push the footer to the bottom of the page.

<body class="d-flex flex-column min-vh-100">
  <div class="container">Other page content..</div>
  <div class="footer mt-auto text-center">
    <span id="bottom"> 
        <hr>
        <p>
            <a href="#"><i class="fab fa-twitter"></i></a>
            <a href="#"><i class="fab fa-instagram"></i></a>
            <a href="#"><i class="fab fa-facebook"></i></a>
       </p>
    </span>
  </div>
</body>

https://codeply.com/p/prWsoALtSD

Also see: Bootstrap 4 Sticky Footer Not Sticking

How do I get a flexbox to have a center fixed and a bottom fixed children together?

Update 1:

Center 'middle' div vertically of the whole 'wrapper'.

.wrapper {
  height: 100px;
  width: 100px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  position: relative;
  border: 1px solid red;
}

.middle,
.bottom {
  background: aqua;
}

.bottom {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
}

<div class="wrapper">
  <div class="middle">middle</div>
  <div class="bottom">bottom</div>
</div>