Drupal Front Page Anchor Tags - Bootstrap

Front Page Anchors

function <YOURTHEME>_links__system_main_menu($variables) {
  $menu = '';
  // Adds heading class
  $menu .= '<h2 class="';
  foreach ($variables['heading']['class'] as $key) {
    $menu .= $key . ' ';
  }
  $menu .= '">Main menu</h2>';

  // Adds UL classes
  $menu .= '<ul class="';
  foreach ($variables['attributes']['class'] as $key) {
    $menu .= $key . ' ';
  }
  $menu .= '" role="menubar">';

  // Adds LI classes
  foreach ($variables['links'] as $key => $value) {
    if (isset($value["#title"])) {
      $menu .= '<li class="mid-' . $key . ' ';
      if (isset($value['#attributes']['class'][0])) {
        $menu .= $value['#attributes']['class'][0];
      }
      $menu .= '" role="presentation">';
      switch ($value['#title']) {
        case 'About':
          $menu .= '<a href="#about"';
          break;

        case 'Home':
          $menu .= '<a href="/"';
          break;
        // WE CAN ADD OTHER CASES HERE LIKE ABOVE
      }
      if (isset($value['#original_link']['options']['attributes']['class'])) {
        $menu .= ' class="';
        foreach ($value['#original_link']['options']['attributes']['class'] as $class) {
          $menu .= $class . ' ';
        }
        $menu .= '"';
      }

      $menu .= ' role="menuitem">' . $value['#title'] . '</a></li>';
    }
  }

  return $menu;
}

u should use the l() function to output links:
https://api.drupal.org/api/drupal/includes%21common.inc/function/l/7