Background image elements on top - php

Question

I've been assigned the task to create a 404.php error page. I just started learning everything and this task is quite difficult. So far I have successuflly:
set up github + atom
clone the repository containing some code
set up MAMP + Wordpress and got the database working
trying to organize all the terms and trying to not confuse them
It's only been 4 days since I started from scratch with basically everything.
I managed to get this code into the 404.php:
> <?php
/**
* The template for displaying 404 pages (Not Found).
**/
get_header(); ?>
<div id="bg">
<img src="<?php echo get_bloginfo('template_directory'); ?> \img\Free-Chalkboard-Backgrounds.jpg" alt="background">
</div>
<header class="entry-header">
<center>
<h1 class="entry-title">404 - Not found</h1>
</center>
</header>
<article id="post-0" class="post error404 no-results not-found">
<div class="entry-content">
<p><big>404 - Die Seite konnte nicht gefunden werden.</big></p>
<?php get_search_form(); ?>
<!-- <img class="img-responsive" src="<?php echo $logoUrl; ?>" alt="Logo - <?php echo get_bloginfo('name'); ?>"> -->
<center><img src="<?php echo get_bloginfo('template_directory'); ?> \img\internet-error-404-file-not-found.jpg" alt="404 not-found" />
</center>
</div>
<!-- .entry-content -->
</article>
<!-- #post-0 -->
<footer>
<ul class="list-inline Impressum">
<li> <a href="https://www.th-nuernberg.de/seitenbaum/impressum/page.html" target="blank">
<alt=>Impressum</a> </li>
<li> |
</li>
<li> <a href="https://www.th-nuernberg.de/institutionen/hochschulkommunikation/ohm-shop/agb/page.html" target="blank">
<alt=>AGB</a> </li>
<li> |
</li>
<li> <a href="https://www.th-nuernberg.de/institutionen/language-center/ueber-uns/page.html" target="blank">
<alt=>Über uns</a> </li>
</ul>
</footer>
<?php get_footer(); ?>
And this is the css:
#bg {
position: fixed;
top: -64%;
left: -55%;
width: 200%;
height: 200%;
}
#bg img {
position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
margin: auto;
min-width: 55%;
min-height: 55%;
}
It looks like this on the localhost-page:
preview of 404
How can I make the other elements be on top of the background? I read several answers but I'm so confused right now that I need a specific hint for my case.
Thanks in advance for helping!

Answer 1

So if i understand you correctly your background is overlapping right now?
I think the property you are searching for is called the z-index.
you probably need to do something like
#bg{
z-index: -1;
}
more info about z-index

Answer 2

Try it once ...
<?php
/**
* The template for displaying 404 pages (Not Found).
**/
get_header(); ?>
<div id="bg">
<img src="<?php echo get_bloginfo('template_directory'); ?> \img\Free-Chalkboard-Backgrounds.jpg" alt="background">
</div>
<header class="entry-header">
<center>
<h1 class="entry-title">404 - Not found</h1>
</center>
</header>
<article id="post-0" class="post error404 no-results not-found">
<div class="entry-content">
<p><big>404 - Die Seite konnte nicht gefunden werden.</big></p>
<?php get_search_form(); ?>
<!-- <img class="img-responsive" src="<?php echo $logoUrl; ?>" alt="Logo - <?php echo get_bloginfo('name'); ?>"> -->
<center><img src="<?php echo get_bloginfo('template_directory'); ?> \img\internet-error-404-file-not-found.jpg" alt="404 not-found" />
</center>
</div>
<!-- .entry-content -->
</article>
<!-- #post-0 -->
<footer>
<ul class="list-inline Impressum">
<li> <a href="https://www.th-nuernberg.de/seitenbaum/impressum/page.html" target="blank">
<alt=>Impressum</a> </li>
<li> |
</li>
<li> <a href="https://www.th-nuernberg.de/institutionen/hochschulkommunikation/ohm-shop/agb/page.html" target="blank">
<alt=>AGB</a> </li>
<li> |
</li>
<li> <a href="https://www.th-nuernberg.de/institutionen/language-center/ueber-uns/page.html" target="blank">
<alt=>Über uns</a> </li>
</ul>
</footer>
<?php get_footer(); ?>
CSS
.bg-img {
background-position: right 45px bottom;
}
#bg {
position: fixed;
top: -64%;
background-position: top center;
left: -55%;
width: 200%;
height: 200%;
}
#bg img {
position: absolute;
top: 0;
background-position: top center;
left: 0;
right: 0;
bottom: 0;
margin: auto;
min-width: 55%;
min-height: 55%;
}