I have a site that broke on the CSS after the first 'leve'.
So
<link rel="stylesheet" href="assets/bootstrap/css/bootstrap.min.css" /> <link rel="stylesheet" href="assets/css/Footer-Dark.css" /> <link rel="stylesheet" href="assets/css/styles.css" />
is the BS exported code that works just fine, as long as you don't need to go to further deeps on your tree.
The second I used this on a template to render a blog, where the blog is generated in code (not a discreet page) as you would imagine the CSS broke.
The reason was clear after having a look at the errors. BS does not put '/' before the path to assets, causing my system to enter the next folder instead, hence breaking the CSS.
Simply solved by exporting the code with the proper relative path as below with the '/'.
<link rel="stylesheet" href="/assets/bootstrap/css/bootstrap.min.css" /> <link rel="stylesheet" href="/assets/css/Footer-Dark.css" /> <link rel="stylesheet" href="/assets/css/styles.css" />
Be very handy as it saves having to edit the code on the server after every export.