HTML Error w/ Document Formatting - html

Question

I'm typing up a document for a nonprofit I'm involved in, and I'm currently working on the headers at the very top of the first page.
It's supposed to be two headers on the same line, one left-aligned and the other right-aligned, and both 13px bold text. It's also supposed to be directly above the title of the document, which is centred in <h1> text style.
Everything is going swimmingly except for the fact that the headers are both left-aligned, and I cannot for the life of me figure out what I'm doing wrong. I know it's not my browser because both StackEdit and WordPress fail to recognise it. And I asked 2 friends to take a look at it, and they can't figure out what's wrong either.
I recognise I probably screwed something up since I'm still learning HTML (I also haven't learned CSS yet), but it has thus far escaped me.
This is what I have:
<span style="text-align:left; font-size:13px"><b>Project Name</b></span>
<span style="text-align:right; font-size:13px"><b>Branch Name, Org
Name</b></span>
<div style=text-align:center><h1>Document Name 1-PubDate</h1></div>

Answer 1

Is this what you are trying to do? Use float css property
<span style="float:left; font-size:13px"><b>Project Name</b></span>
<span style="float:right; font-size:13px"><b>Branch Name, Org Name</b></span>
<div style="text-align:center;clear:both"><h1>Document Name 1-PubDate</h1></div>

Answer 2

Try to use div instead of span like in the following example:
<div style="float:left; text-align:left; font-size:13px; display:inline-block;"><b>Project Name</b></div>
<div style="float:right; text-align:right; font-size:13px; display:inline-block;"><b>Branch Name, Org
Name</b></div>
<div style="clear:both;"></div>
<div style="text-align:center;"><h1>Document Name 1-PubDate</h1></div>
Hope this may help. Best regards,

Answer 3

Because <span> defaults to display:inline, which means it will only grows as wide as its content's width. Try display:inline-block. Also use float to eliminate the white space between them:
span.header
{
display:inline-block;
width:50%;
font-size:13px;
font-weight:bold;
}
span.header.left
{
float:left;
text-align:left;
}
span.header.right
{
float:right;
text-align:right;
}
div.document
{
clear:both;
}
<span class="header left">Project Name</span>
<span class="header right">Branch Name, Org Name</span>
<div class="document"><h1>Document Name 1-PubDate</h1></div>

Answer 4

You are aligning the text of inline elements rather than aligning the elements themselves. If you inspect and look at the spans they are only as large as the text inside them. You can set the width's if you set them to display: inline-block and then the width to 50% and align the text however you want: http://plnkr.co/edit/hQKymbtYp5iBealcEkr3
<span style="display: inline-block; width: 50%; text-align:left; font-size:13px">
<b>Project Name</b>
</span>
<span style="display: inline-block; width: 49%; text-align:right; font-size:13px">
<b>Branch Name, Org Name</b>
</span>
<div style=text-align:center>
<h1>Document Name 1-PubDate</h1>
</div>

Answer 5

I'm going to change things up a bit and make it a bit more semantic (i.e. meaningful)
h1 {text-align:center; /*Center the H1 text*/
clear:both; /*Remove the affects of loats*/}
.preHeader {font-size:13px; font-weight:bold;} /*Set font size and bold pre-head elements*/
.project, .org {width:50%} /*Set common details*/
.project {float:left; } /*Set the project elemetn to the left*/
.org {float:right; text-align:right; } /*Text align the Right side elelment and set it to the right*/
<!-- A Container for your project and organisation elelments -->
<!-- You don't actually need the container, but it seperates it nicely -->
<div class="preHeader">
<div class="project">Project Name</div>
<div class="org">Branch Name, Org Name</div>
</div>
<h1>Title</h1><!-- Already is the width of its parent so don't need to wrap it -->
Learn more about how different elements display. You have block level elements, inline and (inline block) elements, and replaced elements (images and form elements).
Read more about floats here: https://developer.mozilla.org/en-US/docs/Web/CSS/float
And to see a discussion of the merits of floats (and their drawbacks) and the inline-block alternative see: http://robertnyman.com/2010/02/24/css-display-inline-block-why-it-rocks-and-why-it-sucks/
On a side note, get to know some of the handy tools. Pressing f12 in Chrome and Internet Explorer give you the developemt tools for those browsers enabling you to inspect element on a web page and see what styles are affecting it and how they are affecting it as well as giving you the ability to experiment with the styles in place. Firebug for Firefox provides the same functionality.