Image overlapping text and logo not centering on top of image - html

Question

My header image is overlapping my text and it is very much annoying me. Another thing that is buggy is how my logo text leans right of the center of the image. If someone could help me with both that would be awesome.
Here is my code:
https://jsfiddle.net/c2bom0cc/1/
Here are my tags that are probably the most relevant to this:
#index_header {
position: block;
z-index: 0;
left: 0;
top: 0;
height: 100%;
width: 100%;
text-align: center;
vertical-align: middle;
}
#index_header img {
position: block;
float: left;
width: 100%;
height: 100%;
}
.background_title {
position: absolute;
font-family: 'Montserrat', sans-serif;
color: #FFF;
font-size: 64px;
left: 50%;
top: 50%;
}
<div class="page_container">
<div id="index_header">
<a href="#">
<img alt="slider" id="index_headerimg" src="http://www.bakeryandsnacks.com/var/plain_site/storage/images/publications/food-beverage-nutrition/bakeryandsnacks.com/regulation-safety/coles-freshly-baked-claims-false-rules-federal-court-australia/9101085-1-eng-GB/Coles-freshly-baked-claims-false-rules-Federal-Court-Australia.jpg"
/>
<p class="background_title">G.F. Bakery</p>
</a>
</div>
</div>

Answer 1

I let myself hold a few assumptions on your code:
First, by the full height and width of the image, I figured that you want the image as a stretched background image. So I replaced the <img> with background-image (background shorthand) in CSS Backgrounds.
From your question I see that you want the title in the center of the bakery background.
I did not get what text is overlapped by the image.
If you want text below the image, please put it in an element after <div id="index_header">...</div>, as the background is all over that <div>.
I had to add display:inline-block to .background_title class, so that the vertical-align:middle; would take effect.
I removed all the absolute positioning to handle better with all the alignments.
Absolute positioning make you manually set all the top and left, and it's really difficult to do when your code gets bigger.
Here's you new HTML:
<div class="page_container">
<div id="index_header">
<a href="#">
<p class="background_title">G.F. Bakery</p>
</a>
</div>
<p>Some other content...</p> // this text will not be overlapped by
// #index_header as long as #index_header
// isn't absolutely positioned
</div>
Here's your new CSS:
html, body{ // this is instead of having top:0 and left:0 in #index_header
padding: 0;
margin: 0;
}
.page_container {
height: 100%;
width: 100%;
}
#index_header {
height: 200px;
width: 100%;
text-align: center;
vertical-align: middle;
background: url('http://www.bakeryandsnacks.com/var/plain_site/storage/images/publications/food-beverage-nutrition/bakeryandsnacks.com/regulation-safety/coles-freshly-baked-claims-false-rules-federal-court-australia/9101085-1-eng-GB/Coles-freshly-baked-claims-false-rules-Federal-Court-Australia.jpg') no-repeat center center;
background-size: 100% 100%; // this does the stretching
}
.background_title {
display:inline-block; // this is to apply the vertical-align of parent
font-family: 'Montserrat', sans-serif;
color: #FFF;
font-size: 64px;
}
Here's a JSFiddle
Hope this helps.

Answer 2

If you want your text to be under your image and centered, remove the following code:
.background_title {
position: absolute;
}
Just removing the position will move your text under your image and centered.