来自PHP的HTML有一些不受欢迎的过度缩进

I'd like to control exactly the indentation of my HTML that's generated by PHP but I'm unable to remove some of it. An example is this HTML source code:

<table id="structure">
<tr>
    <td id="navigation">
        <p>Hello!</p>   </td>

Why are the <td> and <p> lines indented like this? Can I modify that?

The main PHP that generated it was

<table id="structure">
<tr>
<td id="navigation"><?php echo navigation($data_page,$data_subj);?>

and the "navigation" function starts with

function navigation($data_page,$data_subj){
$output = "<p>Hello!</p>";
return $output;
}

(The real navigation is a <ul> with <li> elements containing <ul>'s in turn and I'm trying to render it readable in the HTML source code by adding and \t\t for indentation levels.)

For new line try ' '. The sign for new line is depends on your file encoding and the operating system you are using.