如何将项目准确放置在CSS的目标位置

Alright, so this is my HTML right now.

<?php
    session_start();
?>
<!DOCTYPE html>
<html>
    <head>
        <title>GeoVillage - A Community</title>
        <link rel="stylesheet" href="style.css">
    </head>
    <body>
        <div id=header>
            <img id=logo src="/logo.png" alt="GeoVillage Community" style="width:500px;height:128px;">
            <span id=logreg>
                <?php
                    if(isset($_SESSION['loggedon']) && $_SESSION['loggedon'] == true){
                        echo '<a href=/logout>
                            <img id=logout src="/logout.png" alt="Logout">
                            </a>';
                    } else {
                        echo '<a href=/login>
                            <img id=login src="/login.png" alt="Login">
                            </a>';
                        echo '<a href=/login/register.php>
                            <img id=register src="/register.png" alt="Register">
                            </a>';
                    }
                ?>
            </span>
        </div>
        <ul>
            <li><a href="/vatsim">FSX/X-P/P3D Vatsim Online Material</a></li>
            <li><a href="/dev2">Development Page</a></li>
        </ul>
        <?php
            echo($_SESSION["loggedon"]);
        ?>
    </body>
</html>

And this is my CSS file.

body{
    background-color: #33ccff;
    margin: 0px;
}

#header{
    display:inline;

Right now, the Login and Register buttons are at the top, but aligned essentialy with the bottom of the banner. How would i position it so it would be aligned with the top of the banner?

Try this

#logreg {vertical-align: top;display: inline-block;}

METHOD 1

This makes the width of your header wider, to allow the login / register buttons to fit within the header container. The #logoreg CSS then adds a margin to the top of the login / register button container, which centers it with the logo when the right px amount is specified.

CSS:

#header {
  display: block;
  width: 105%;
}
#logreg {
  float: right;
  margin-top: 15px;
}

METHOD 2

Change the width of your banner image.

<img id="logo" src="/logo.png" alt="GeoVillage Community" style="width: 700px;height:96px;">

Then put this in your CSS:

#logreg {
  margin-top: 15px;
  float: right;
  display: inline-block;
}