URL重写后样式表不起作用

Here is my .htaccess code

RewriteEngine On
RewriteRule ^Blog?$ blog.php
RewriteRule ^Details/([0-9]+)/([0-9a-zA-Z]+) blog-single.php?id=$1

<a href="Details/<?php echo $row['id'];?>/<?php echo $row['heading'];?>" class="view"><?php echo $row['heading'];?></a>

After URL rewritting

http://example.com/Details/15/Top-10-Tips-for-Starting-Your-Small-Business

but on blog-single.php Style sheets not working.

On my page source url is http://example.com/Details/15/assets/bootstrap/css/bootstrap.min.css

how to remove 15 in my rewrited URL or how to assign path from rewrited URL

In this cases you can address css and js files from root directory like this:

http://example.com/css/style.css

and css files load on all pages