displaying wordpress content on external webpage with correct formatting

I have created a function in wordpress that retrieves a page by the post_name, the function is working fine however when i call the function on my external website and display the page/post content the formatting is incorrect.

Here is how i display it:

$page = get_page_by_post_name($_GET["id"], OBJECT, 'page');
query_posts('p='.$page->ID.'');
echo '<div id="page-title">'.$page->post_title.'</div>';
echo $page->post_content;

So i format the text and images in the wordpress editor and then when they display, its just one big block of text. any ideas?

Here is the CSS I have on my external page:

html,body {
    margin:0;
    padding:0;
    overflow-x:hidden;
    font-family:Arial;
    height: 100%;
}
h1, h2, h3, h4, h5, h6 {
    clear: both;
    font-weight: 700;
    margin: 36px 0 12px;
}
h1 {
    font-size: 26px;
    line-height: 1.3846153846;
}
h2 {
    font-size: 24px;
    line-height: 1;
}
h3 {
    font-size: 22px;
    line-height: 1.0909090909;
}
h4 {
    font-size: 20px;
    line-height: 1.2;
}
h5 {
    font-size: 18px;
    line-height: 1.3333333333;
}
h6 {
    font-size: 16px;
    line-height: 1.5;
}
h1:first-child, h2:first-child, h3:first-child, h4:first-child, h5:first-child, h6:first-child {
    margin-top: 0;
}
p {
    margin: 0 0 24px;
}