feat: more modular styling

moves styling over to sass and makes each individual theme easier to customize

src/lib/Navigation.svelte

@@ -23,8 +23,7 @@ import { get } from 'svelte/store';
     }
 
 </script>
-<div style="background-color: #292929" class="mb-4">
-    <Navbar color="light" light expand="lg">
+    <Navbar color="light" light expand="lg" class="mb-4">
         <NavbarBrand>pk-webs</NavbarBrand>
         <NavbarToggler on:click={toggle}></NavbarToggler>
         <Collapse {isOpen} navbar expand="lg">
@@ -59,5 +58,4 @@ import { get } from 'svelte/store';
                 </NavItem>
             </Nav>
         </Collapse>
-    </Navbar>
-</div>
+    </Navbar>