Someone

$media_count is a numbered list generated from theme_settings and themename.info


function aether_preprocess_page(&$variables, $hook) {

    $base_grid_prefix = $grid["prefix{$media_count}"];
    $grid_width = $grid["width{$media_count}"];
    $variables['grid_width'] = $grid_width;

}

page.tpl.php

<div class="header-inner <?php print $variables['grid_width']; ?>">