print view changes stylesheet order

Hi.
If I call 'node/id' everything works well.
My custom stylesheet is in 'ntn/css/print_ntn.css'.

Viewing the page source of 'node/id' shows print_ntn.css correct after bootstrap.css:

</style>
<link type="text/css" rel="stylesheet" href="//cdn.jsdelivr.net/bootswatch/3.3.7/yeti/bootstrap.css" media="all" />
<style>
@import url("https://ntn.els.schule/sites/all/themes/bootstrap/css/3.3.7/overrides-yeti.min.css?ourtt3");
@import url("https://ntn.els.schule/sites/all/themes/ntn/css/style.css?ourtt3");
@import url("https://ntn.els.schule/sites/all/themes/ntn/smartmenus101/addons/bootstrap/jquery.smartmenus.bootstrap.css?ourtt3");
@import url("https://ntn.els.schule/sites/all/themes/ntn/css/print_ntn.css?ourtt3");
</style>

Unfortunately not on the print view. Viewing the page source of 'print/id' shows print_ntn.css before bootstrap.css:

<style>
...
@import url("https://ntn.els.schule/sites/all/themes/ntn/css/print_ntn.css?ourtt3");
</style>
<link type="text/css" rel="stylesheet" href="//cdn.jsdelivr.net/bootswatch/3.3.7/yeti/bootstrap.css" media="all" />
<style>
@import url("https://ntn.els.schule/sites/all/themes/bootstrap/css/3.3.7/overrides-yeti.min.css?ourtt3");
</style>

Using Drupal 7.56